Imaging apparatus

ABSTRACT

An imaging apparatus capable of performing phase difference detection while allowing light to enter an imaging device is provided. 
     An imaging unit ( 1 ) includes an imaging device ( 10 ) configured to perform photoelectric conversion on received light and allow light to pass therethrough and a phase difference detection section ( 20 ) configured to perform phase difference detection on received light which has passed through the imaging device ( 10 ). The imaging device ( 10 ) includes a color-purpose light receiving section ( 11   b,    11   b , . . . ) including color filters ( 15   r,    15   g,    15   b ) and configured to obtain color information and an brightness-purpose light receiving section ( 11   b,    11   b , . . . ) configured to obtain brightness information and receive a larger amount of light than the color-purpose light receiving section ( 11   b,    11   b , . . . ). The phase difference detection section ( 20 ) performs phase difference detection on received light which has passed through at least the brightness-purpose light receiving section ( 11   b,    11   b , . . . ).

TECHNICAL FIELD

The present invention relates to an imaging apparatus including animaging device for performing photoelectric conversion.

BACKGROUND ART

In recent years, digital cameras that convert an object image into anelectrical signal using an imaging device such as a charge coupleddevice (CCD) image sensor and a complementary metal-oxide semiconductor(CMOS) image sensor, digitize the electrical signals, and record theobtained digital signals, have been widely used.

Single-lens reflex digital cameras include a phase difference detectionsection for detecting a phase difference between object images, and havethe phase difference detection AF function of performing autofocus(hereinafter simply referred to as “AF”) by the phase differencedetection section. Since the phase difference detection AF functionallows detection of defocus direction and a defocus amount, the movingtime of a focus lens can be reduced, thereby achieving fast-focusing(see, for example, PATENT DOCUMENT 1). In known single-lens reflexdigital cameras, provided is a movable mirror capable of moving in orout of an optical path from a lens tube to an imaging device in order tolead light from an object to a phase difference detection section.

In so-called compact digital cameras, the autofocus function by video AFusing an imaging device (see, for example, PATENT DOCUMENT 2) isemployed. Therefore, in compact digital cameras, a mirror for leadinglight from an object to a phase difference detection section is notprovided, thus achieving reduction in the size of compact digitalcameras. In such compact digital cameras, autofocus can be performedwith light incident on the imaging device. That is, it is possible toperform various types of processing using the imaging device, including,for example, obtaining an image signal from an object image formed onthe imaging device to display the object image on an image displaysection provided on a back surface of the camera or to record the objectimage in a recording section, while performing autofocus. In general,this autofocus function by video AF advantageously has higher accuracythan that of phase difference detection AF.

CITATION LIST Patent Document

PATENT DOCUMENT 1: Japanese Patent Publication No. 2007-163545

PATENT DOCUMENT 2: Japanese Patent Publication No. 2007-135140

SUMMARY OF THE INVENTION Technical Problem

However, a defocus direction cannot be instantaneously detected by videoAF. For example, when contrast detection AF is employed, a focus isdetected by detecting a contrast peak, but a contrast peak direction,i.e., a defocus direction, cannot be detected unless a focus lens isshifted to back and forth from its current position, or the like.Therefore, it takes a long time to detect a focus.

In view of reducing the time required for detecting a focus, phasedifference detection AF is more advantageous. However, in an imagingapparatus such as a single-lens reflex digital camera according toPATENT DOCUMENT 1, employing phase difference detection AF, a movablemirror has to be moved to be on an optical path from a lens tube to animaging device in order to lead light from an object to a phasedifference detection section. Thus, the imaging apparatus cannot performvarious processes using the imaging device, while performing phasedifference detection AF. In addition, even if the time necessary fordetecting a focus with phase difference detection AF is reduced, it isnecessary to move the movable mirror in switching the path of incidentlight between a path toward the phase difference detection section and apath toward the imaging device. This movement of the movable mirrordisadvantageously causes a time lag.

It is therefore an object of the present invention to provide an imagingapparatus capable of detecting a phase difference while allowing lightto enter an imaging device.

Solution to the Problem

An imaging apparatus according to the present invention includes: animaging device configured to perform photoelectric conversion onreceived light and allow light to pass therethrough; and a phasedifference detection section configured to perform phase differencedetection on received light which has passed through the imaging device.The imaging device includes a color-purpose light receiving sectionincluding a color filter and configured to obtain color information andan brightness-purpose light receiving section configured to obtainbrightness information and receive a larger amount of light than thecolor-purpose light receiving section. The phase difference detectionsection performs phase difference detection on received light which haspassed through at least the brightness-purpose light receiving section.

ADVANTAGES OF THE INVENTION

According to the present invention, the imaging device includes anbrightness-purpose light receiving section configured to obtainbrightness information and receive a larger amount of light than acolor-purpose light receiving section, which is configured to obtaincolor information. Thus, a larger amount of light is allowed to enter aportion of the imaging device in which the brightness-purpose lightreceiving section is provided. Accordingly, light is transmitted throughthe imaging device via at least a portion in which thebrightness-purpose light receiving section is provided, and can bereceived by the phase difference detection section. As a result, it ispossible to allow the phase difference detection section to performphase difference detection, while allowing light to enter the imagingdevice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an imaging device according to a firstembodiment of the present invention.

FIG. 2 is a cross-sectional view of an imaging unit.

FIG. 3 is a cross-sectional view of the imaging device.

FIG. 4 is a plan view of a phase difference detection unit.

FIG. 5 is a perspective view of an imaging unit according to avariation.

FIG. 6 is a cross-sectional view of an imaging device of the variation.

FIG. 7 is a cross-sectional view illustrating a cross section of animaging unit according to another variation, corresponding to FIG. 2.

FIG. 8 is a cross-sectional view illustrating a cross section of theimaging unit of the another variation, which is perpendicular to thecross section thereof corresponding to FIG. 2.

FIG. 9 is a block diagram of a camera according to a second embodimentof the present invention.

FIG. 10 is a flowchart showing a flow in shooting operation by phasedifference detection AF before a release button is pressed all the waydown.

FIG. 11 is a flowchart showing a basic flow in shooting operationincluding shooting operation by phase difference detection AF after therelease button is pressed all the way down.

FIG. 12 is a flowchart showing a flow in shooting operation by contrastdetection AF before the release button is pressed all the way down.

FIG. 13 is a flowchart showing a flow in shooting operation by hybrid AFbefore the release button is pressed all the way down.

FIG. 14 is a flowchart showing a flow in shooting operation by phasedifference detection AF of a variation before the release button ispressed all the way down.

FIG. 15 is a flowchart showing a flow in shooting operation by hybrid AFof the variation before the release button is pressed all the way down.

FIG. 16 is a flowchart showing a flow in shooting operation in acontinuous shooting mode before the release button is pressed all theway down.

FIG. 17 is a flowchart showing a flow in shooting operation in thecontinuous shooting mode after the release button is pressed all the waydown.

FIG. 18 is a flowchart showing a flow in shooting operation in a lowcontrast mode before the release button is pressed all the way down.

FIG. 19 is a flowchart showing a flow in shooting operation in which AFfunction is switched according to the type of interchangeable lensesbefore the release button is pressed all the way down.

FIG. 20 is a block diagram of a camera according to a third embodimentof the present invention.

FIG. 21 is a view for describing configurations of a quick return mirrorand a light shield plate. FIG. 21(A) shows the quick return mirror in aretreat position, FIG. 21(B) shows the quick return mirror positionedbetween the retreat position and a reflection position, and FIG. 21(C)shows the quick return mirror in the reflection position.

FIG. 22 is a flowchart showing a flow in a finder shooting mode beforethe release button is pressed all the way down.

FIG. 23 is a flowchart showing a flow in the finder shooting mode afterthe release button is pressed all the way down.

FIG. 24 is a flowchart showing a flow in a live view shooting modebefore the release button is pressed all the way down.

FIG. 25 is a flowchart showing a flow in the live view shooting modeafter the release button is pressed all the way down.

DESCRIPTION OF REFERENCE CHARACTERS

-   1, 301 imaging unit (imaging apparatus)-   10, 210 imaging device-   11 a, 211 a substrate-   11 b R pixel, G pixel, B pixel (color-purpose light receiving    section), and colorless pixel (brightness-purpose light receiving    section)-   15 r red color filter-   15 g green color filter-   15 b blue color filter light transmitting portion (thin portion)-   20, 320 phase difference detection unit (phase difference detection    section)-   23 a, 323 a separator lens-   24 a, 324 a line sensor (sensor)-   100, 200 camera (imaging apparatus) body control section (control    section)

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be specifically describedhereinafter with reference to the drawings.

First Embodiment

FIG. 2 illustrates an imaging unit 1 as an imaging apparatus accordingto the present invention. The imaging unit 1 includes an imaging device10 for converting an object image into an electrical signal; a package31 for holding the imaging device 10; and a phase difference detectionunit 20 for performing focus detection using a phase differencedetection method.

The imaging device 10 is an interline type CCD image sensor and, asshown in FIG. 3, includes a photoelectric conversion section 11 made ofa semiconductor material, vertical registers 12, transfer paths 13,masks 14, filters 15, and microlenses 16.

The photoelectric conversion section 11 includes a substrate 11 a and aplurality of light receiving sections (also referred to as “pixels”) 11b, 11 b, . . . arranged on the substrate 11 a.

The substrate 11 a is a Si (silicon)-based substrate. Specifically, thesubstrate 11 a is a Si single crystal substrate or asilicon-on-insulator (SOI) wafer. In particular, an SOI substrate has asandwich structure of a SiO₂ thin film and Si thin films, and chemicalreaction can be stopped at the SiO₂ film in etching or like processing.Thus, in terms of performing stable substrate processing, it isadvantageous to use an SOI substrate.

Each of the light receiving sections 11 b is made of a photodiode, andabsorbs light to generate electrical charge. The light receivingsections 11 b, 11 b, . . . are respectively provided in micro pixelregions each having a square shape and arranged in a matrix on thesubstrate 11 a (see, FIG. 1).

The vertical registers 12 are respectively provided for the lightreceiving sections 11 b, and serve to temporarily store electricalcharge stored in the light receiving sections 11 b. Specifically, theelectrical charge stored in the light receiving sections 11 b istransferred to the vertical registers 12. The electrical chargetransferred to the vertical registers 12 is transferred to a horizontalregister (not shown) via the transfer paths 13, and then, to anamplifier (not shown). The electrical charge transferred to theamplifier is amplified and pulled out as an electrical signal.

The masks 14 are provided so that the light receiving sections 11 b areexposed toward an object and the masks 14 cover the vertical registers12 and the transfer paths 13 to prevent light from entering the verticalregisters 12 and the transfer paths 13.

Each of the filters 15 and an associated one of the microlenses 16 areprovided in each light receiving section 11 b, (i.e., each micro pixelregion having a square shape).

The microlenses 16 collect light to cause the light to enter the lightreceiving sections 11 b. The light receiving sections 11 b can beefficiently irradiated with light by the microlenses 16.

The filters 15 include: transparent filters 15 c through which varioustypes of light is transmitted, irrespective of the type of colors; andcolor filters 15 r, 15 g, and 15 b through each of which light of only aspecific color is transmitted.

In the imaging device 10, as illustrated in FIG. 1, assuming that fourlight receiving sections 11 b, 11 b, . . . (or four pixel regions)arranged adjacent to one another in two rows and two columns are arepeat unit, the color filters 15 r, 15 g, and 15 b are provided inthree light receiving sections 11 b, 11 b, and 11 b, whereas thetransparent filter 15 c is provided in the other light receiving section11 b.

More specifically, in four light receiving sections 11 b, 11 b, . . . inthe repeat unit, the green color filter (i.e., a color filter having ahigher transmittance in a green visible light wavelength range than inthe other color visible light wavelength ranges) 15 g is provided in thelight receiving section 11 b diagonal to the light receiving section 11b in which the transparent filter 15 c is provided, the red color filter(i.e., a color filter having a higher transmittance in a red visiblelight wavelength range than in the other color visible light wavelengthranges) 15 r is provided in one of the light receiving sections 11 brespectively adjacent to the light receiving section 11 b in which thetransparent filter 15 c is provided, and the blue color filter (i.e., acolor filter having a higher transmittance in a blue visible lightwavelength range than in the other color visible light wavelengthranges) 15 b is provided in the other light receiving section 11 badjacent to the light receiving section 11 b in which the transparentfilter 15 c is provided. In other words, in so-called Bayer primarycolor filters, one of generally two green color filters among four colorfilters adjacent to one another in two rows and two columns is removedso as to obtain an optically transparent state. The light receivingsections 11 b, 11 b, . . . in which the color filters 15 r, 15 g, and 15b are provided constitute color-purpose light receiving sections (i.e.,light receiving sections for color information), and the light receivingsection 11 b in which the transparent filter 15 c is providedconstitutes an brightness-purpose light receiving section (i.e., lightreceiving sections for brightness information).

In this manner, the transparent filter 15 c and the color filters 15 r,15 g, and 15 b arranged adjacent to one another in two rows and twocolumns are regularly arranged on the substrate 11 a.

In the thus-configured imaging device 10, light collected by themicrolenses 16, 16, . . . enters the color filters 15 r, 15 g, and 15 band the transparent filters 15 c. Only part of the light of a colorassociated with each of the filters is transmitted through the filter,and is applied on the light receiving sections 11 b, 11 b, . . . . Eachof the light receiving sections 11 b absorbs the light to generateelectrical charge. The electrical charge generated by the lightreceiving sections 11 b is transferred to an amplifier via the verticalregisters 12 and the transfer paths 13, and is output as an electricalsignal.

Specifically, the amount of received light of a color associated witheach filter is obtained as an output from each of the light receivingsections 11 b, 11 b, . . . in which the color filters 15 r, 15 g, and 15b are provided. On the other hand, the amount of received light of whitelight is obtained as an output from the light receiving section 11 b inwhich the transparent filter 15 c is provided.

In this manner, the imaging device 10 performs photoelectric conversionat the light receiving sections 11 b, 11 b, . . . provided throughoutthe entire imaging plane, thereby converting an object image formed onthe imaging plane into an electrical signal.

In this case, a plurality of light transmitting portions 17, 17, . . .for transmitting irradiation light are formed in the substrate 11 a. Thelight transmitting portions 17 are formed by cutting, polishing, oretching an opposite surface (hereinafter also referred to as a “backsurface”) 11 c of the substrate 11 a to a surface thereof on which thelight receiving sections 11 b are provided to provide concave-shapedrecesses, and each of the light transmitting portions 17 has a thicknesssmaller than that of portion of the substrate 11 a around each of thelight transmitting portions 17. More specifically, each of the lighttransmitting portions 17 includes a recess-bottom surface 17 a having asmallest thickness and inclined surfaces 17 b, 17 b connecting therecess-bottom surface 17 a and the back surface 11 c.

Each of the light transmitting portions 17 in the substrate 11 a isformed to have a thickness which allows light to be transmitted throughthe light transmitting portion 17, so that part of irradiation lightonto the light transmitting portion 17 is not converted into electricalcharge and is transmitted through the photoelectric conversion section11. For example, the substrate 11 a may be formed so that each ofportions thereof located in the light transmitting portions 17 has athickness of 2-3 μm. Then, about 50% of light having a longer wavelengththan that of near infrared light can be transmitted through the lighttransmitting portions 17.

Each of the inclined surfaces 17 b, 17 b is set to be at an angle atwhich light reflected by the inclined surface 17 b is not directed tocondenser lenses 21 a, 21 a, . . . of the phase difference detectionunit 20, which will be described later, when light is transmittedthrough the light transmitting portions 17. Thus, formation of anon-real image on a line sensor 24 a, which will be described later, isprevented.

Each of the light transmitting portions 17 forms a thin portion whichtransmits light entering the imaging device 10, i.e., which allows lightentering the imaging device 10 to pass therethrough. The term “pass”includes the concept of “transmit” at least in this specification.

In this case, in the light receiving section 11 b in which thetransparent filter 15 c is provided in the imaging device 10,attenuation of incident light being transmitted through the transparentfilter 15 c is smaller than that being transmitted through the lightreceiving sections 11 b, 11 b, . . . in which the color filters 15 r, 15g, and 15 b are provided, and thus, a larger amount of light reaches thephotoelectric conversion section 11. Accordingly, in the light receivingsection 11 b in which the transparent filter 15 c is provided, theamount of light which is not converted into electrical charge andtransmitted through the photoelectric conversion section 11 is largerthan that in the light receiving sections 11 b, 11 b, . . . in which thecolor filters 15 r, 15 g, and 15 b are provided. That is, a largeramount of light incident on the light receiving section 11 b in whichthe transparent filter 15 c is provided is transmitted through the lighttransmitting portions 17, than light incident on the light receivingsections 11 b, 11 b, . . . in which the color filters 15 r, 15 g, and 15b are provided.

The light transmitting portions 17 in the substrate 11 a may have athickness with which not only light incident on the light receivingsection 11 b in which the transparent filter 15 c is provided but alsolight incident on the light receiving sections 11 b, 11 b, . . . inwhich the color filters 15 r, 15 g, and 15 b are provided is transmittedthrough the light transmitting portions 17, or may have a thickness withwhich only light incident on the light receiving section 11 b in whichthe transparent filter 15 c is provided is transmitted through the lighttransmitting portions 17. To transmit a larger amount of light throughthe substrate 11 a, the former thickness is preferable. To minimize theamount of light transmitted through the substrate 11 a to increase theamount of light converted into electrical charge through photoelectricconversion, the latter thickness is preferable.

The imaging device 10 configured in the above-described manner is heldin the package 31 (see, FIG. 2). The package 31 forms a holding portion.

Specifically, the package 31 includes a flat bottom plate 31 a providedwith a frame 32, and upright walls 31 b, 31 b, . . . provided in fourdirections. The imaging device 10 is mounted on the frame 32 so as to besurrounded by the upright walls 31 b, 31 b, . . . in four directions,and is electrically connected to the frame 32 via bonding wires.

Moreover, a cover glass 33 is attached to ends of the upright walls 31b, 31 b, . . . of the package 31 so as to cover the imaging plane (i.e.,the surface on which the light receiving sections 11 b, 11 b, . . . areprovided) of the imaging device 10. The imaging plane of the imagingdevice 10 is protected by the cover glass 33 from attachment of dust andthe like.

In this case, the same number of openings 31 c, 31 c, . . . as thenumber of the light transmitting portions 17, 17, . . . are formed inthe bottom plate 31 a of the package 31 so as to penetrate the bottomplate 31 a and to be located at positions respectively corresponding tothe light transmitting portions 17, 17, . . . of the imaging device 10.With these openings 31 c, 31 c, . . . , light which has passed throughthe imaging device 10 reaches the phase difference detection unit 20,which will be described later. The openings 31 c form light passingportions.

In the bottom plate 31 a of the package 31, the openings 31 c do nothave to be necessarily formed so as to penetrate the bottom plate 31 a.That is, as long as light which has passed through the imaging device 10can reach the phase difference detection unit 20, a configuration inwhich transparent portions or semi-transparent portions are formed inthe bottom plate 31 a, or a similar configuration may be employed.

The phase difference detection unit 20 is provided to the back surface(i.e., an opposite surface to a surface facing an object) of the imagingdevice 10, and receives light which has passed through the imagingdevice 10 to perform phase difference detection. Specifically, the phasedifference detection unit 20 converts the received light into anelectrical signal for use in distance measurement. The phase differencedetection unit 20 forms a phase difference detection section.

As shown in FIGS. 2 and 4, the phase difference detection unit 20includes: a condenser lens unit 21; a mask member 22; a separator lensunit 23; a line sensor unit 24; and a module frame 25 for attaching thecondenser lens unit 21, the mask member 22, the separator lens unit 23,and the line sensor unit 24. The condenser lens unit 21, the mask member22, the separator lens unit 23, and the line sensor unit 24 are arrangedin this order from the imaging device 10 along the thickness of theimaging device 10.

The plurality of condenser lenses 21 a, 21 a, . . . integrated into asingle unit form the condenser lens unit 21. The same number of thecondenser lenses 21 a, 21 a, . . . as the number of the lighttransmitting portions 17, 17, . . . are provided. Each of the condenserlenses 21 a collects incident light. The condenser lenses 21 a collectlight which has passed through the imaging device 10 and is spreadingout therein, and guide the light to separator lenses 23 a of theseparator lens unit 23, which will be described later. Each of thecondenser lenses 21 a is formed into a circular column shape, and anincident surface 21 b of the condenser lens 21 a has a convex shape.

Since an incident angle of light entering each of the separator lenses23 a is reduced by providing the condenser lenses 21 a, an aberration ofthe separator lenses 23 a can be reduced, and a distance between objectimages on the line sensor 24 a which will be described later can bereduced. As a result, the size of each of the separator lenses 23 a andthe line sensor 24 a can be reduced. In addition, when a focus positionof an object image from the imaging optical system greatly diverges fromthe imaging unit 1 (specifically, greatly diverges from the imagingdevice 10 of the imaging unit 1), the contrast of the image remarkablydecreases. In this embodiment, however, due to the size-reduction effectof the condenser lenses 21 a and the separator lenses 23 a, reduction incontrast can be prevented, so that a focus detection range can beincreased. If highly accurate phase difference detection around a focusposition is performed, or if the separator lenses 23 a, the line sensors24 a, and the like have sufficient dimensions, the condenser lens unit21 does not have to be provided.

The mask member 22 is provided between the condenser lens unit 21 andthe separator lens unit 23. In the mask member 22, two mask openings 22a, 22 a are formed in a part thereof corresponding to each of theseparator lenses 23 a. That is, the mask member 22 divides a lenssurface of each of the separator lenses 23 a into two areas, so thatonly the two areas are exposed toward the condenser lenses 21 a. Morespecifically, the mask member 22 performs pupil division to divide lightcollected by each condenser lens 21 a into two light bundles and causesthe two light bundles to enter the separator lens 23 a. The mask member22 can prevent harmful light from one of adjacent two of the separatorlenses 23 a from entering the other one of the adjacent two separatorlenses 23 a. Note that the mask member 22 does not have to be provided.

The separator lens unit 23 includes a plurality of separator lenses 23a, 23 a, . . . . In other words, the separator lenses 23 a, 23 a, . . .are integrated into a single unit to form the separator lens unit 23. Inthe same manner as that for the condenser lenses 21 a, 21 a, . . . , thesame number of the separator lenses 23 a, 23 a, . . . as the number ofthe light transmitting portions 17, 17, . . . are provided. Each of theseparator lenses 23 a forms two identical object images on the linesensor 24 a from two light bundles which have passed through the maskmember 22 and has entered the separator lens 23 a.

The line sensor unit 24 includes a plurality of line sensors 24 a, 24 a,. . . and a mounting portion 24 b on which the line sensors 24 a, 24 a,. . . are mounted. In the same manner as for the condenser lenses 21 a,21 a, . . . , the same number of the line sensors 24 a, 24 a, . . . asthe number of the light transmitting portions 17, 17, . . . areprovided. Each of the line sensors 24 a receives a light image to beformed on an imaging plane, and converts the image into an electricalsignal. That is, a distance between the two object images can bedetected from an output of the line sensor 24 a, and a shift amount(i.e., a defocus amount: Df amount) of a focus of an object image to beformed on the imaging device 10 and the direction (i.e., the defocusdirection) in which the focus is shifted can be obtained, based on thedistance. The Df amount, the defocus direction, and the like will alsobe referred to as “defocus information” hereinafter.

The condenser lens unit 21, the mask member 22, the separator lens unit23, and the line sensor unit 24, configured in the above-describedmanner, are provided within the module frame 25.

The module frame 25 is a member formed to have a frame shape, and anattachment portion 25 a is provided along an inner periphery of themodule frame 25 so as to protrude inwardly. On one side of theattachment portion 25 a facing the imaging device 10, a first attachmentportion 25 b and a second attachment portion 25 c are formed in astepwise manner. On the other side of the attachment portion 25 a, whichis opposite side to the side facing the imaging device 10, a thirdattachment portion 25 d is formed.

The mask member 22 is attached to a side of the second attachmentportion 25 c of the module frame 25 located closer to the imaging device10, and the condenser lens unit 21 is attached to the first attachmentportion 25 b. As shown in FIGS. 2 and 4, the condenser lens unit 21 andthe mask member 22 are formed so that a peripheral portion of each ofthe condenser lens unit 21 and the mask member 22 fits in the moduleframe 25 when being attached to the first attachment portion 25 b andthe second attachment portion 25 c, and thus, the condenser lens unit 21and the mask member 22 are positioned relative to the module frame 25.

The separator lens unit 23 is attached to a side of the third attachmentportion 25 d of the module frame 25 located opposite to the imagingdevice 10. The third attachment portion 25 d is provided withpositioning pins 25 e and direction reference pins 25 f, each of whichprotrudes in an opposite direction to the condenser lens unit 21. Theseparator lens unit 23 is provided with positioning holes 23 b anddirection reference holes 23 c respectively corresponding to thepositioning pins 25 e and the direction reference pins 25 f. Thediameters of the positioning pins 25 e and the positioning holes 23 bare determined so that the positioning pins 25 e fit in the positioningholes 23 b. On the other hand, the diameters of the direction referencepins 25 f and the direction reference holes 23 c are determined so thatthe direction reference pins 25 f loosely fit in the direction referenceholes 23 c. That is, the attitude of the separator lens unit 23 such asthe direction in which the separator lens unit 23 is attached to thethird attachment portion 25 d is defined by respectively inserting thepositioning pins 25 e and the direction reference pins 25 f of the thirdattachment portion 25 d in the positioning holes 23 b and the directionreference holes 23 c, and the position of the separator lens unit 23 isdetermined relative to the third attachment portion 25 d by providing aclose fit of the positioning pins 25 e with the positioning holes 23 b.Thus, when the attitude and position of the separator lens unit 23 aredetermined and the separator lens unit 23 is attached, the lens surfaceof each of the separator lenses 23 a, 23 a, . . . is directed toward thecondenser lens unit 21, and faces an associated one of the mask openings22 a, 22 a.

In the above-described manner, the condenser lens unit 21, the maskmember 22, and the separator lens unit 23 are attached to the moduleframe 25, while being held at determined positions. That is, thepositional relationship among the condenser lens unit 21, the maskmember 22, and the separator lens unit 23 is determined by the moduleframe 25.

Then, the line sensor unit 24 is attached to the module frame 25 fromthe back side (which is an opposite side to the side facing thecondenser lens unit 21) of the separator lens unit 23. In this case, theline sensor unit 24 is attached to the module frame 25, while being heldin a position which allows light transmitted through each of theseparator lenses 23 a to enter an associated one of the line sensors 24a.

In above-described manner, the condenser lens unit 21, the mask member22, the separator lens unit 23, and the line sensor unit 24 are attachedto the module frame 25, and thus, the condenser lenses 21 a, 21 a, . . ., the mask member 22, the separator lenses 23 a, 23 a, . . . , and theline sensor 24 a, 24 a, . . . are arranged so as to be located atdetermined positions so that light incident on the condenser lenses 21a, 21 a, . . . is transmitted through the condenser lenses 21 a, 21 a, .. . to enter the separator lenses 23 a, 23 a, . . . via the mask member22, and then, light which has been transmitted through the separatorlenses 23 a, 23 a, . . . forms an image on each of the line sensors 24a, 24 a, . . . .

The imaging device 10 and the phase difference detection unit 20configured in the above-described manner are joined together.Specifically, the imaging device 10 and the phase difference detectionunit 20 are configured such that the openings 31 c of the package 31 inthe imaging device 10 closely fit the condenser lenses 21 a in the phasedifference detection unit 20. That is, with the condenser lenses 21 a,21 a, . . . in the phase difference detection unit 20 respectivelyinserted in the openings 31 c, 31 c, . . . of the package 31 in theimaging device 10, the module frame 25 is bonded to the package 31.Thus, the imaging device 10 and the phase difference detection unit 20are joined together while being held in the positions relative to eachother. As described above, the condenser lenses 21 a, 21 a, . . . , theseparator lenses 23 a, 23 a, . . . , and the line sensors 24 a, 24 a, .. . are integrated into a single unit, and then are attached as a signalunit to the package 31.

The imaging device 10 and the phase difference detection unit 20 may beconfigured such that all of the openings 31 c, 31 c, . . . closely fitall the condenser lenses 21 a, 21 a, . . . . Alternatively, the imagingdevice 10 and the phase difference detection unit 20 may be alsoconfigured such that only some of the openings 31 c, 31 c, . . . closelyfit associated ones of the condenser lenses 21 a, 21 a, . . . , and therest of the openings 31 c, 31 c, . . . loosely fit associated ones ofthe condenser lenses 21 a, 21 a, . . . . In the latter case, the imagingdevice 10 and the phase difference detection unit 20 are preferablyconfigured such that one of the condenser lenses 21 a and one of theopenings 31 c located closest to the center of the imaging plane closelyfit each other to determine positions in the imaging plane, andfurthermore, one of the condenser lenses 21 a and one of the openings 31c located most distant from the center of the imaging plane closely fiteach other to determine peripheral positions (i.e., rotation angles) ofthe condenser lens 21 a and the opening 31 c which are located at thecenter of the imaging plane.

As a result of connecting the imaging device 10 and the phase differencedetection unit 20, the condenser lens 21 a, a pair of the mask openings22 a, 22 a of the mask member 22, the separator lens 23 a, and the linesensor 24 a are arranged in the back side of the substrate 11 a tocorrespond to each of the light transmitting portions 17.

The operation of the imaging unit 1 configured in the above-describedmanner will be described hereinafter.

When light enters the imaging unit 1 from an object, the light istransmitted through the cover glass 33, and enters the imaging device10. The light is collected by the microlenses 16 of the imaging device10, and then, is transmitted through the filters 15, so that light ofcolors associated with the filters 15 reaches the light receivingsections 11 b. The light receiving sections 11 b absorb light togenerate electrical charge. The generated electrical charge istransferred to the amplifier via the vertical registers 12 and thetransfer paths 13, and is output as an electrical signal. In thismanner, each of the light receiving sections 11 b converts light into anelectrical signal throughout the entire imaging plane, and thereby, theimaging device 10 converts an object image formed on the imaging planeinto an electrical signal for generating an image signal.

In the light transmitting portions 17, 17, . . . , part of light appliedto the imaging device 10 is transmitted through the imaging device 10.In particular, in the light receiving section 11 b in which thetransparent filter 15 c is provided, attenuation of light beingtransmitted through the transparent filter 15 c is smaller than thatpassing through the color filters 15 r, 15 g, and 15 b, and thus, alarger amount of light reaches the photoelectric conversion section 11.Consequently, in the light transmitting portions 17, a larger amount oflight is transmitted through a portion associated with the lightreceiving section 11 b in which the transparent filter 15 c is provided.

The light transmitted through the imaging device 10 enters the condenserlenses 21 a, 21 a, . . . which closely fit the openings 31 c, 31 c, . .. of the package 31. The light which has been collected after beingtransmitted through each of the condenser lenses 21 a is divided intotwo light bundles when passing through each pair of mask openings 22 a,22 a formed in the mask member 22, and then, enters each of theseparator lenses 23 a. Light subjected to pupil division is transmittedthrough the separator lens 23 a and identical object images are formedon two positions on the line sensor 24 a. As the photoelectricconversion section 11 does, the line sensor 24 a performs photoelectricconversion on the amount of light received by each light receivingsection to generate an electrical signal, and then outputs theelectrical signal.

In this case, the light transmitting portions 17 include a plurality oflight receiving sections 11 b in which the transparent filters 15 c areprovided. Specifically, light transmitted through the light receivingsections 11 b, 11 b, . . . in which the transparent filters 15 c areprovided enters one condenser lens 21 a, one separator lens 23 a, andone line sensor 24 a.

The imaging unit 1 operating in the manner described above is connectedto a control section (not shown) corresponding to, for example, a bodycontrol section 5 of a second embodiment, which will be described later,and an output of the imaging unit 1 is processed in the manner describedbelow, thereby generating an image signal and detecting a focus state.In this embodiment, the control section is not provided in the imagingunit 1, but may be provided in the imaging unit 1.

The control section obtains an object image formed on the imaging planeas an electrical signal by obtaining positional information on each ofthe light receiving sections 11 b and output data corresponding to theamount of received light in this light receiving section 11 b.

In this case, in the light receiving sections 11 b, 11 b, . . . , evenwhen the same amount of light is received, the amount of accumulatedelectrical charge differs among different wavelengths of light. Thus,output data from the light receiving sections 11 b, 11 b, . . . of theimaging device 10 is corrected according to the types of the colorfilters 15 r, 15 g, and 15 b and transparent filters 15 c respectivelyprovided to the light receiving sections 11 b, 11 b, . . . . Forexample, a correction amount for each pixel is determined so thatoutputs of the R pixel 11 b, the G pixel 11 b, the B pixel 11 b, and thecolorless pixel 11 b become at the same level when each of the R pixel11 b to which the red color filter 15 r is provided, the G pixel 11 b towhich the green color filter 15 g is provided, the B pixel 11 b to whichthe blue color filter 15 b is provided, and the colorless pixel 11 b towhich the transparent filter 15 c is provided receives the same amountof light corresponding to the color of each color filter.

Further, in this embodiment, the presence of the light transmittingportions 17, 17, . . . in the substrate 11 a causes the photoelectricconversion efficiency in the light transmitting portions 17, 17, . . .to be lower than that of the other portions. That is, even with the sameamount of received light, the amount of accumulated electrical charge inthe pixels 11 b, 11 b, . . . provided at positions associated with thelight transmitting portions 17, 17, . . . is smaller than that in theother portions. Consequently, if the same image processing is performedon both of output data output from the pixels 11 b, 11 b, . . . providedat positions associated with the light transmitting portions 17, 17, . .. and output data output from the pixels 11 b, 11 b, . . . provided atthe other positions, an image of a portion associated with the lighttransmitting portions 17, 17, . . . might be inappropriately captured(e.g., shooting image might be dark). To prevent this problem, an outputfrom each of the pixels 11 b in the light transmitting portions 17, 17,. . . is corrected (e.g., amplified) so as to eliminate the influence ofthe light transmitting portions 17, 17, . . . .

The decrease in output varies depending on the wavelength of light.Specifically, as the wavelength increases, the transmittance of thesubstrate 11 a increases. Thus, the amount of light which is transmittedthrough the substrate 11 a varies depending on the types of the colorfilters 15 r, 15 g, and 15 b and the transparent filter 15 c. In view ofthis phenomenon, the correction for eliminating the influence of thelight transmitting portions 17 on each pixel 11 b associated with thelight transmitting portion 17 is performed while varying the correctionamount according to the wavelength of light received by the pixel 11 b.That is, for each pixel 11 b associated with the light transmittingportion 17, the correction amount is increased as the wavelength oflight received by the pixel 11 b increases.

In this case, in each pixel 11 b, the correction amount for eliminatingthe difference in the amount of accumulated charge depending on the typeof color of received light is determined as described above, and inaddition to the correction for eliminating the difference in the amountof accumulated charge depending on the type of a color of receivedlight, correction for eliminating the influence of the lighttransmitting portions 17 is also performed. That is, the amount ofcorrection for eliminating the influence of the light transmittingportions 17 is the difference between the correction amount for thepixels 11 b associated with the light transmitting portions 17 and thecorrection amount for pixels associated with the portions except for thelight transmitting portions 17 and receiving light of the same color asthe pixels 11 b associated with the light transmitting portions 17. Inthis embodiment, the correction amount differs among colors according tothe relationship described below. With this relationship, a stable imageoutput can be obtained.

Lk>Rk>Gk>Bk  (1)

whereLk: the colorless-pixel correction amount for the light transmittingportions 17—the colorless-pixel correction amount for positions exceptfor the light transmitting portions 17;Rk: R-pixel correction amount for the light transmitting portions 17—theR-pixel correction amount for positions except for the lighttransmitting portions 17;Gk: G-pixel correction amount for the light transmitting portions 17—theG-pixel correction amount for positions except for the lighttransmitting portions 17; and

Bk: B-pixel correction amount for the light transmitting portions 17—theB-pixel correction amount for positions except for the lighttransmitting portions 17.

Specifically, since light with every wavelength enters the colorlesspixels, the different in the correction amount for the colorless pixelsis the largest. Among colors of red, green, and blue, red with a longwavelength has the highest transmittance, and thus the difference in thecorrection amount for the red pixels is the largest. In addition, sinceblue with a short wavelength has the lowest transmittance, thedifference in the correction amount for the blue pixels is the smallest.

That is, the correction amount of an output from each pixel 11 b in theimaging device 10 is determined depending on whether the pixel 11 b islocated at a position associated with the light transmitting portion 17and on the type of the filter 15 associated with the pixel 11 b.

For example, the correction amount of each of the red, green, and bluepixels 11 b are determined such that the white balance is equal for eachof an image displayed by an output from the light transmitting portion17 and an image displayed by an output from a portion except for thelight transmitting portions 17. On the other hand, the correction amountof the colorless pixel 11 b is determined such that the brightness isequal for each of an output from the light transmitting portion 17 andan output from a portion except for the light transmitting portions 17.For these correction amounts, the difference relative to a referencelight source (e.g., a D light source) having the same light amount isprepared as a default coefficient.

The control section performs interpolation of the colorless pixel 11 b.Specifically, output data from the colorless pixel 11 b includes onlybrightness information, and does not include color information.Accordingly, information on the color of the colorless pixel 11 b isinterpolated using output data from adjacent pixels 11 b.

Specifically, interpolation (standard interpolation) of a color signalof green of a colorless pixel 11 b is performed using the average valueof outputs of four G pixels 11 b, 11 b, . . . diagonally adjacent to thecolorless pixel 11 b. Alternatively, in the four G pixels 11 b, 11 b, .. . each of which is located diagonally adjacent to the colorless pixel11 b, change in output of one pair of the G pixels 11 b, 11 b adjacentto each other in one diagonal direction is compared to change in outputof the other pair of the G pixels 11 b, 11 b adjacent to each other inthe other diagonal direction, and then, interpolation (slopeinterpolation) of a color signal of green of the colorless pixel 11 b isperformed using the average value of outputs of the pair of the G pixels11 b, 11 b located diagonally adjacent whose change in output is larger,or the average value of outputs of the pair of the G pixels 11 b, 11 blocated diagonally adjacent whose change in output is smaller. Assumethat a pixel desired to be interpolated is an edge of a focus object. Ifinterpolation is performed using the pair of the light receivingsections 11 b, 11 b whose change in output is larger, the edge isundesirably caused to be loose. Therefore, the pair of the lightreceiving sections 11 b, 11 b whose change in output is smaller is usedwhen each of the changes is larger than or equal to a predeterminedthreshold, and the pair of the light receiving sections 11 b, 11 b whosechange in output is larger is used when each of the changes is smallerthan the predetermine threshold so that as small change rate (slope) aspossible is employed.

Then, the control section generates an image signal made of brightnessinformation and color information.

Specifically, the control section obtains brightness information on eachof the pixels 11 b by multiplying output data of each pixel 11 b by apredetermined coefficient. For the colorless pixel 11 b, output data isused as brightness information without change. In addition, the controlsection interpolates color information on each pixel 11 b using outputdata of adjacent pixels 11 b, 11 b, . . . around the pixel 11 b. Morespecifically, output data of each pixel 11 b is the amount of receivedlight of specific one of red, green, and blue. That is, output data ofred, output data of green, and output data of blue are obtained from theR pixel 11 b, G pixel 11 b, and B pixel 11 b, respectively. For thecolorless pixel 11 b, interpolation has been previously performed usingoutput data from the G pixel, as described above, and thus, output dataof green is obtained. Thus, based on output data obtained from thepixels 11 b, 11 b, . . . , the control section interpolates output dataof the other two colors which are not present in each pixel 11 b.Consequently, red, green, and blue output data is generated for eachpixel 11 b. Since output data of the three colors includes brightnessinformation, color information including no brightness information canbe generated by subtracting brightness information for each pixel 11 bobtained in the manner described above from output data of theassociated color. In this manner, the control section obtains brightnessinformation and color information for each pixel 11 b.

If it is not necessary to distinguish brightness information from colorinformation, image processing may be performed using color informationincluding brightness information.

Further, the control section performs different image processings forbrightness information and color information obtained for each pixel 11b, and eventually, an image signal is generated by synthesizing thebrightness information with the color information.

The color space in processing by the control section is not limited toRGB, and may be converted, by, for example, Lab conversion, into anothercolor space to perform processing.

In the foregoing description, the control section first interpolatescolor information on the colorless pixel 11 b using output data fromadjacent pixels 11 b. Alternatively, in interpolating a color which isnot present in each pixel 11 b, information on the colorless pixel 11 bmay be interpolated for three colors.

In this manner, an image signal of an object image formed on the imagingplane of the imaging device 10 is obtained.

In this case, with respect to brightness information, since output datafrom the R pixel 11, the G pixel 11 b, and the B pixel 11 b includesbrightness information as well as color information, the brightnessinformation on each of the pixels 11 b, 11 b, . . . can be obtained fromoutput data thereof, thereby obtaining brightness information with highresolution. With respect to color information, output data on adeficient color is interpolated using output data on adjacent pixels 11b, 11 b, . . . , and especially for the colorless pixel 11 b, all thethree colors of red, green, and blue are eventually interpolated.However, human eyes have a lower resolution for detecting colorinformation than that for detecting brightness information. Thus,synthesis of the color information and the high-resolution brightnessinformation together can provide a color image having a high resolutionfor human eyes.

By correcting and interpolating an output from the imaging device 10 inthe manner described above, an image signal of an object image can beproperly captured even by the imaging device 10 provided with thecolorless pixels 11 b in which the transparent filters 15 c areprovided. In this case, outputs of the light receiving sections 11 b, 11b, . . . in which the color filters 15 r, 15 g, 15 b are provided areused principally for obtaining color information (e.g., RGB describedabove and ab in Lab), and an output of the light receiving section 11 bin which the transparent filter 15 c is provided is used principally forobtaining brightness information.

An electrical signal output from the line sensor unit 24 is also inputto the control section. The control section may be identical to, ordifferent from, the control section of the imaging device 10. Thecontrol section can obtain the distance between two object images formedon the line sensor 24 a, based on the output from the line sensor unit24, and then, can detect a focus state of an object image formed on theimaging device 10 from the obtained distance. For example, when twoobject images are correctly formed on the imaging device 10 (i.e., infocus) after being transmitted through an imaging lens, the two objectimages are located at predetermined reference positions with apredetermined reference distance therebetween. In contrast, when objectimages are formed before the imaging device 10 in the optical axisdirection (i.e., front focus), the distance between the object images issmaller than the reference distance when the object images are in focus.When object images are formed behind the imaging device 10 in theoptical axis direction (i.e., back focus), the distance between the twoobject images is larger than the reference distance when the objectimage is in focus. That is, an output from the line sensor 24 a isamplified, and then, operation by an arithmetic circuit obtainsinformation regarding whether an object image is in focus or not,whether the object is in front focus or back focus, and the Df amount.

Accordingly, in this embodiment, since the light receiving sections 11b, 11 b, . . . includes light receiving sections, i.e., the colorlesspixels 11 b, for obtaining brightness information where no color filtersare provided, a larger amount of light can enter the photoelectricconversion section 11 through the light receiving sections 11 b forobtaining brightness information, and part of the light can betransmitted to the back side of the imaging device 10. In addition,since the phase difference detection unit 20 is provided at the backside of the imaging device 10, light transmitted through the imagingdevice 10 is received at the phase difference detection unit 20 so thatphase difference detection can be performed. As a result, it is possibleto perform phase difference detection using the phase differencedetection unit 20 provided at the back side of the imaging device 10,while allowing light to enter the imaging device 10 to performprocessing using the imaging device 10.

Further, the substrate 11 a can be configured such that the presence ofthe light transmitting portions 17 in the substrate 11 a allows light tobe easily transmitted therethrough, and the light transmitting portions17 and the colorless pixels 11 b can increase the transmittance of lighttoward the back side of the imaging device 10. Consequently, a largeramount of light can enter the phase difference detection unit 20, andthus, phase difference detection can be precisely performed by the phasedifference detection unit 20. Alternatively, in allowing a minimumamount of light for phase difference detection by the phase differencedetection unit 20 to be transmitted toward the back side of the imagingdevice 10, the thickness of the light transmitting portions 17 in thesubstrate 11 a can be increased as much as possible. That is, if thethickness of the substrate 11 a is excessively reduced, the amount oflight converted into electrical charge by the photoelectric conversionsection 11 decreases. However, if the thickness of the substrate 11 a isincreased as much as possible, the amount of electrical charge convertedby the photoelectric conversion section 11 can be increased.Accordingly, the amount of light converted into electrical charge in theimaging device 10 and the amount of light entering the phase differencedetection unit 20 can be appropriately balanced.

As long as brightness information is obtained, even chromatic filtersmay be provided in the light receiving sections 11 b for brightnessinformation. Note that the presence of the transparent filters, insteadof the chromatic filters, can reduce attenuation of light, and canfurther increase the transmittance of light transmitted through theimaging device 10.

Further, the light receiving sections 11 b, 11 b, . . . at positionsassociated with the light transmitting portions 17 include a pluralityof light receiving sections 11 b, 11 b, . . . for brightness informationin which no color filters are provided. Thus, the set of the condenserlens 21 a, the separator lens 23 a, and the line sensor 24 a providedfor each light transmitting portion 17 receives not only lighttransmitted through one light receiving section 11 b for brightnessinformation but also light transmitted through the plurality of lightreceiving sections 11 b, 11 b, . . . for brightness information.Accordingly, phase difference detection can be performed with asufficient amount of received light, thereby accurately detecting afocus state.

Furthermore, light from the plurality of light receiving sections 11 b,11 b, . . . for brightness information enters a single set of thecondenser lens 21 a, the separator lens 23 a, and the line sensor 24 a.This configuration is advantageous because the size of the set of thecondenser lens 21 a, the separator lens 23 a, and the line sensor 24 ais not restricted by the size of pixels. That is, advantageously, thesize of one set of the condenser lens 21 a, the separator lens 23 a, andthe line sensor 24 a does not cause any problem in increasing theresolution of the imaging device 10 by reducing the size of pixels.

On the other hand, since the light receiving sections 11 b forbrightness information in which no color filters are provided cannotobtain color information, the resolution of color information in theentire imaging plane of the imaging device 10 decreases by the valuecorresponding to the light receiving sections 11 b, 11 b, . . . forbrightness information. However, brightness information can also beobtained from the light receiving sections 11 b, 11 b, . . . in whichthe color filters 15 r, 15 g, and 15 b are provided, and human eyes aremore sensitive to brightness information than to color information.Thus, even when the resolution of color information decreases to somedegree, synthesis of the color information with high-resolutionbrightness information allows a high-resolution color image to humaneyes to be obtained.

In addition, in relation to the imaging device 10 configured to transmitlight therethrough, the openings 31 c, 31 c, . . . are formed in thebottom plate 31 a of the package 31 for housing the imaging device 10,and thereby, light transmitted through the imaging device 10 is allowedto easily reach the back side of the package 31. In addition, the phasedifference detection unit 20 is disposed in the back side of the package31, and thus, a configuration in which light transmitted through theimaging device 10 is received at the phase difference detection unit 20can be easily obtained.

As long as light transmitted through the imaging device 10 can passthrough the openings 31 c, 31 c, . . . formed in the bottom plate 31 aof the package 31 toward the back side of the package 31, anyconfiguration can be employed. However, by forming the openings 31 c, 31c, . . . as through holes, it is possible to allow light transmittedthrough the imaging device 10 to reach the back side of the package 31without attenuating the light.

With the condenser lenses 21 a, 21 a, . . . provided so as to closelyfit the openings 31 c, 31 c, . . . , positioning of the phase differencedetection unit 20 relative to the imaging device 10 can be performedusing the openings 31 c, 31 c, . . . . When the condenser lenses 21 a,21 a, . . . are not provided, the separator lenses 23 a, 23 a, . . . maybe configured to closely fit the openings 31 c, 31 c, . . . . Thus,positioning of the phase difference detection unit 20 relative to theimaging device 10 can be performed in the same manner.

In addition, the condenser lenses 21 a, 21 a, . . . can be provided soas to penetrate the bottom plate 31 a of the package 31 to approach thesubstrate 11 a. Thus, the imaging unit 1 can be configured as a compactsize imaging unit.

In this embodiment, repeat units in which the transparent filters 15 cand the color filters 15 r, 15 g, and 15 b are mixed are arrangedthroughout the imaging device 10. However, the present invention is notlimited to this configuration. For example, repeat units in which thetransparent filters 15 c and the color filters 15 r, 15 g, and 15 b aremixed may be provided only in portions where the light transmittingportions 17 are provided, whereas the color filters 15 r, 15 g, and 15 bmay be arranged in a so-called Bayer pattern in portions where the lighttransmitting portions 17 are not provided. Specifically, in the imagingdevice 10, assuming that four light receiving sections 11 b, 11 b, . . .(or four pixel regions) arranged adjacent to one another in two rows andtwo columns are a repeat unit, in this repeat unit, two green colorfilters 15 g and 15 g are arranged in one diagonal direction, and a redcolor filter 15 r and a blue color filter 15 b are arranged in anotherdiagonal direction. On the other hand, in portions of the imaging device10 in which the light transmitting portions 17 are provided, in a repeatunit made of four light receiving sections 11 b, 11 b, . . . arrangedadjacent to one another in two rows and two columns, the green colorfilter 15 g is provided in the light receiving section 11 b located in adiagonal position to the light receiving section 11 b in which thetransparent filter 15 c is provided, the red color filter 15 r isprovided in one of the light receiving sections 11 b located adjacent tothe light receiving section 11 b in which the transparent filter 15 c isprovided, and the blue color filter 15 b is provided in the other one ofthe light receiving sections 11 b located adjacent to the lightreceiving section 11 b in which the transparent filter 15 c is provided.

The filters provided in the brightness-purpose light receiving sections11 b are not limited to the transparent filters 15 c. As long as theamount of received light with respect to white light in thebrightness-purpose light receiving sections 11 b is larger than theamount of received light in the color-purpose light receiving sections11 b, 11 b, . . . in which the color filters 15 r, 15 g, and 15 b areprovided, color filters may be provided instead of the transparentfilters. For example, a color filter (i.e., a chromatic filter) may beprovided as long as the filter has a transmittance with respect to whitelight higher than those of the three color filters 15 r, 15 g, and 15 b.In the case of providing this color filter, brightness information canbe calculated by multiplying an output of the brightness-purpose lightreceiving section 11 b in which the color filter is provided by apredetermined coefficient. In addition, color information can also beobtained by subtracting the brightness information from the output ofthe light receiving section 11 b.

In this embodiment, the transparent filter is provided in the lightreceiving section 11 b in which the color filters 15 r, 15 g, and 15 bare not provided among the four light receiving sections 11 b, 11 b, . .. . However, this transparent filter does not have to be provided. Thatis, instead of the transparent filters, a material, such as resin,constituting the microlenses 16 may fill the pixel regions.

Further, the color filters 15 r, 15 g, and 15 b are not limited toprimary color filters, and may be complementary color filters, forexample.

Each of the light transmitting portions 17 has a smaller thickness thanportions of the substrate 11 a located around the light transmittingportion 17. However, the configuration of a light transmitting portionis not limited thereto. For example, the thickness of the entiresubstrate 11 a may be determined so that part of irradiation light ontothe substrate 11 a is transmitted, in a sufficient amount, through thesubstrate 11 a, to reach the phase difference detection unit 20 providedin the back side of the substrate 11 a. In such a case, the entiresubstrate 11 a serves as a light transmitting portion.

Further, in this embodiment, the light transmitting portions 17 allowlight incident on the light receiving sections 11 b, 11 b, . . . inwhich the color filters 15 r, 15 g, and 15 b are provided to also passthrough the substrate 11 a. However, the present invention is notlimited to this configuration. For example, the thickness of thesubstrate 11 a may be set at such a value that transmits light incidenton the light receiving section 11 b in which the transparent filter 15 cis provided, but does not transmit light incident on the light receivingsections 11 b, 11 b, . . . in which the color filters 15 r, 15 g, and 15b are provided, i.e., allows at least light entering the light receivingsection 11 b in which the transparent filter 15 c is provided to betransmitted through the substrate 11 a.

According to this embodiment, three light transmitting portions 17, 17,and 17 are formed in the substrate 11 a, and three sets of the condenserlens 21 a, the separator lens 23 a, and the line sensor 24 a areprovided so as to correspond to the three light transmitting portions17, 17, and 17. However, the configuration including those components isnot limited thereto. The number of sets of those components is notlimited to three, but may be any number. For example, as shown in FIG.5, nine light transmitting portions 17, 17, . . . may be formed in thesubstrate 11 a, and accordingly, nine sets of the condenser lens 21 a,the separator lens 23 a, and the line sensor 24 a may be provided.

Further, the imaging device 10 is not limited to a CCD image sensor, butmay be, as shown in FIG. 6, a CMOS image sensor.

An imaging device 210 is a CMOS image sensor, and includes aphotoelectric conversion section 211 made of a semiconductor material,transistors 212, signal lines 213, masks 214, color filters 215, andmicrolenses 216.

The photoelectric conversion section 211 includes a substrate 211 a, andlight receiving sections 211 b, 211 b, . . . each made of a photodiode.The transistors 212 are respectively provided for the light receivingsections 211 b. Electrical charge accumulated in the light receivingsections 211 b is amplified by the transistors 212, and is output to theoutside via the signal lines 213. The configurations of the masks 214and the microlenses 216 are the same as those of the masks 14 and themicrolenses 16. The filters 215 are the color filters 15 r, 15 g, and 15b, and do not include transparent filters. That is, a material, such asresin, constituting the microlenses 216 fills the pixel regions, insteadof transparent filters.

As in the CCD image sensor, the light transmitting portions 17, 17, . .. for allowing irradiation light to be transmitted therethrough areformed in the substrate 211 a. The light transmitting portions 17 areformed by cutting, polishing, or etching an opposite surface(hereinafter also referred to as a “back surface”) 211 c of thesubstrate 211 a to a surface thereof on which the light receivingsections 211 b are provided to provide concave-shaped recesses, and eachof the light transmitting portions 17 has a thickness smaller than thatof part of the substrate 211 a around each of the light transmittingportions 17.

In the CMOS image sensor, the amplification factor of the transistor 212can be determined for each light receiving section 211 b. Therefore, bydetermining the amplification factor of each transistor 212 based onwhether each of the light receiving sections 211 b is located at aposition associated with the light transmitting portion 17 and on thetype of color of the color filter 15 associated with each lightreceiving section 211 b, a case where parts of an image corresponding tothe light transmitting portions 17, 17, . . . are not properly capturedcan be avoided.

Furthermore, the phase difference detection unit 20 is not limited tothe above-described configuration. For example, a configuration in whicha condenser lens is not provided may be employed. Furthermore, asanother option, a configuration in which each condenser lens and acorresponding separator lens are formed as a single unit may beemployed.

As another example, as shown in FIGS. 7 and 8, a phase differencedetection unit 320 in which a condenser lens unit 321, a mask member322, a separator lens unit 323, and a line sensor unit 324 are arrangedin the parallel direction to the imaging plane of the imaging device 10in the back side of the imaging device 10 may be employed.

Specifically, the condenser lens unit 321 is configured such that aplurality of condenser lenses 321 a, 321 a, . . . are integrated into asingle unit, and includes an incident surface 321 b, a reflectionsurface 321 c, and an output surface 321 d. That is, in the condenserlens unit 321, light collected by the condenser lenses 321 a, 321 a, . .. is reflected on the reflection surface 321 c at an angle of about 90degrees, and is output from the output surface 321 d. As a result, alight path of light which has been transmitted through the imagingdevice 10 and has entered the condenser lens unit 321 is bentsubstantially perpendicularly by the reflection surface 321 c, and isoutput from the output surface 321 d to be directed to a separator lens323 a of the separator lens unit 323. The light which has entered theseparator lens 323 a is transmitted through the separator lens 323 a,and an image is formed on a line sensor 324 a.

The condenser lens unit 321, the mask member 322, the separator lensunit 323, and the line sensor unit 324 configured in the above-describedmanner are provided within a module frame 325.

The module frame 325 is formed to have a box shape, and a step potion325 a for attaching the condenser lens unit 321 is provided in themodule frame 325. The condenser lens unit 321 is attached to the steppotion 325 a so that the condenser lenses 321 a, 321 a, . . . faceoutward from the module frame 325.

Moreover, in the module frame 325, an attachment wall potion 325 b forattaching the mask member 322 and the separator lens unit 323 isprovided so as to upwardly extend at a part facing the output surface321 d of the condenser lens unit 321. An opening 325 c is formed in theattachment wall potion 325 b.

The mask member 322 is attached to a side of the attachment wall potion325 b located closer to the condenser lens unit 321. The separator lensunit 323 is attached to an opposite side of the attachment wall potion325 b to the side closer to the condenser lens unit 321.

Thus, the light path of light transmitted through the imaging device 10is bent in the back side of the imaging device 10, and thus, thecondenser lens unit 321, the mask member 322, the separator lens unit323, the line sensor unit 324, and the like can be arranged in theparallel direction to the imaging plane of the imaging device 10,instead of in the thickness direction of the imaging device 10.Therefore, a dimension of the imaging unit 301 in the thicknessdirection of the imaging device 10 can be reduced. That is, an imagingunit 301 can be formed as a compact size imaging unit 301.

As described above, as long as light transmitted through the imagingdevice 10 can be received in the back side of the imaging device 10 andthen phase difference detection can be performed thereon, a phasedifference unit having any configuration may be employed.

Second Embodiment

A camera 100 as an imaging apparatus according to a second embodiment ofthe present invention will be described.

As shown in FIG. 9, the camera 100 is a single-lens reflex digitalcamera with interchangeable lenses, and includes, as major components, acamera body 4 having a major function as a camera system, andinterchangeable lenses 7 removably attached to the camera body 4. Theinterchangeable lenses 7 are attached to a body mount 41 provided on afront face of the camera body 4. The body mount 41 is provided with anelectric contact piece 41 a.

—Configuration of Camera Body—

The camera body 4 includes: an imaging unit 1 according to the firstembodiment for capturing an object image as a shooting image; a shutterunit 42 for adjusting an exposure state of the imaging unit 1; anoptical low pass filter (OLPF) 43, also serving as an IR cutter, forremoving infrared light of the object image entering the imaging unit 1and reducing the moire phenomenon; an image display section 44 made of aliquid crystal monitor and configured to display the shooting image, alive view image, and various information; and a body control section 5.

The camera body 4 includes: a power switch 40 a for turning the camerasystem on/off; a release button 40 b which is operated by a user whenthe user performs focusing and releasing operations; and settingswitches 40 c and 40 d for turning various shooting modes and functionson/off.

When the camera system is turned on by the power switch 40 a, power issupplied to each part of the camera body 4 and the interchangeable lens7.

The release button 40 b operates as a two-stage switch. Specifically,autofocusing, AE, or the like, which will be described later, isperformed by pressing the release button 40 b halfway down, andreleasing is performed by pressing the release button 40 b all the waydown.

An AF setting switch 40 c is a switch for switching an autofocusfunction among three states, which will be described later. The camerabody 4 is configured such that the autofocus function used in one of thethree states by switching the AF setting switch 40 c.

A continuous-shooting setting switch 40 d is a switch forsetting/canceling a continuous shooting mode, which will be describedlater. The camera body 4 is configured such that a picture shooting modecan be switched between a normal shooting mode and a continuous shootingmode by operating the continuous-shooting setting switch 40 d.

The setting switches 40 c and 40 d may be used for switching otherselection items in a menu for selecting a desired camera shootingfunction.

The imaging unit 1 is configured to be movable by a blur correction unit45 in a plane perpendicular to an optical axis X.

The body control section 5 includes: a body microcomputer 50; anonvolatile memory 50 a; a shutter control section 51 for controllingdriving of the shutter unit 42; an imaging unit control section 52 forcontrolling operation of the imaging unit 1 and performing A/Dconversion on an electrical signal from the imaging unit 1 to output theconverted signal to the body microcomputer 50; an imagereading/recording section 53 for reading image data from an imagestorage section 58 such as a card type recording medium or an internalmemory and recording image data in the image storage section 58; animage recording control section 54 for controlling the imagereading/recording section 53; an image display control section 55 forcontrolling display of the image display section 44; a blur detectionsection 56 for detecting the amount of an image blur generated due to ashake of the camera body 4; and a correction unit control section 57 forcontrolling the blur correction unit 45. The body control section 5constitutes a control section which generates an image signal based onan output of an imaging device 10.

The body microcomputer 50 is a control device for controlling of corefunctions of the camera body 4, and performs control of varioussequences. The body microcomputer 50 includes, for example, a CPU, aROM, and a RAM. Programs stored in the ROM are read by the CPU, andthereby, the body microcomputer 50 executes various functions.

The body microcomputer 50 is configured to receive input signals fromthe power switch 40 a, the release button 40 b, and each of the settingswitches 40 c and 40 d, and output control signals to the shuttercontrol section 51, the imaging unit control section 52, the imagereading/recording section 53, the image recording control section 54,the correction unit control section 57, and the like, thereby causingthe shutter control section 51, the imaging unit control section 52, theimage reading/recording section 53, the image recording control section54, the correction unit control section 57, and the like to executecontrol operations. The body microcomputer 50 performsinter-microcomputer communication with a lens microcomputer 80, whichwill be described later.

For example, according to an instruction of the body microcomputer 50,the imaging unit control section 52 performs A/D conversion on anelectrical signal from the imaging unit 1 to output the converted signalto the body microcomputer 50. The body microcomputer 50 performspredetermined image processing on the received electrical signal togenerate an image signal. Then, the body microcomputer 50 transmits theimage signal to the image reading/recording section 53, and alsoinstructs the image recording control section 54 to record and displayan image, and thereby, the image signal is stored in the image storagesection 58 and is transmitted to the image display control section 55.The image display control section 55 controls the image display section44, based on the transmitted image signal to cause the image displaysection 44 to display an image.

As the predetermined image processing, the body microcomputer 50performs, for example, correction of outputs from the light receivingsections 11 b and interpolation of pixels, as described above.

In the nonvolatile memory 50 a, various information (unit information)on the camera body 4 is stored. The unit information includes, forexample, model information (i.e., unit specific information) provided tospecify the camera body 4, such as a name of a manufacturer, aproduction date, and a model number of the camera body 4, versioninformation on software installed in the body microcomputer 50, andfirmware update information, information regarding whether or not thecamera body 4 includes sections for correcting an image blur in, forexample, the blur correction unit 45 and the blur detection section 56,information regarding detection performance of the blur detectionsection 56, such as a model number, detection ability, and the like,error history, and the like. Such information as listed above may bestored in a memory section of the body microcomputer 50, instead of thenonvolatile memory 50 a.

The blur detection section 56 includes an angular velocity sensor fordetecting movement of the camera body 4 due to hand shake and the like.The angular velocity sensor outputs a positive/negative angular velocitysignal according to the direction in which the camera body 4 moves,using, as a reference, an output in a state where the camera body 4stands still. In this embodiment, two angular velocity sensors areprovided to detect two directions, i.e., a yawing direction and apitching direction. After being subjected to filtering, amplification,and the like, the output angular velocity signal is converted into adigital signal by the A/D conversion section, and then, is given to thebody microcomputer 50.

—Configuration of Interchangeable Lens—

The interchangeable lens 7 forms an imaging optical system for formingan object image on the imaging unit 1 in the camera body 4, andincludes, as major components, a focus adjustment section 7A forperforming focusing an aperture adjustment section 7B for adjusting anaperture, a lens image blur correction section 7C for adjusting anoptical path to correct an image blur, and a lens control section 8 forcontrolling operation of the interchangeable lens 7.

The interchangeable lens 7 is attached to the body mount 41 of thecamera body 4 via a lens mount 71. The lens mount 71 is provided with anelectric contact piece 71 a which is electrically connected to theelectric contact piece 41 a of the body mount 41 when theinterchangeable lens 7 is attached to the camera body 4.

The focus adjustment section 7A includes a focus lens group 72 foradjusting a focus. The focus lens group 72 is movable in the opticalaxis X direction in a zone from a closest focus position predeterminedas a standard for the interchangeable lens 7 to an infinite focusposition. When a focus position is detected using a contrast detectionmethod which will be described later, the focus lens group 72 has to bemovable forward and backward from a focus position in the optical axis Xdirection. Therefore, the focus lens group 72 has a lens shift marginzone which allows the focus lens group 72 to move forward and backwardin the optical axis X direction to a further distance beyond the zoneranging from the closest focus position to the infinite focus position.

The aperture adjustment section 7B includes an aperture section 73 foradjusting an aperture.

The lens image blur correction section 7C includes a blur correctionlens 74, and a blur correction lens driving section 74 a for shiftingthe blur correction lens 74 in a plane perpendicular to the optical axisX.

The lens control section 8 includes a lens microcomputer 80, anonvolatile memory 80 a, a focus lens group control section 81 forcontrolling operation of the focus lens group 72, a focus drivingsection 82 for receiving a control signal from the focus lens groupcontrol section 81 to drive the focus lens group 72, an aperture controlsection 83 for controlling operation of the aperture section 73, a blurdetection section 84 for detecting a blur of the interchangeable lens 7,and a blur correction lens unit control section 85 for controlling theblur correction lens driving section 74 a.

The lens microcomputer 80 is a control device for controlling corefunctions of the interchangeable lens 7, and is connected to eachcomponent mounted on the interchangeable lens 7. Specifically, the lensmicrocomputer 80 includes a CPU, a ROM, and a RAM and, when programsstored in the ROM are read by the CPU, various functions can beexecuted. For example, the lens microcomputer 80 has the function ofsetting a lens image blur correction system (e.g., the blur correctionlens driving section 74 a) to be a correction possible state or acorrection impossible state, based on a signal from the bodymicrocomputer 50. Due to the contact between the electric contact piece71 a provided to the lens mount 71 with the electric contact piece 41 aprovided to the body mount 41, the body microcomputer 50 is electricallyconnected to the lens microcomputer 80, so that information can betransmitted/received between the body microcomputer 50 and the lensmicrocomputer 80.

In the nonvolatile memory 80 a, various information (e.g., lensinformation) for the interchangeable lens 7 is stored. The lensinformation includes, for example, model information (i.e., lensspecific information) provided to specify the interchangeable lens 7,such as a name of a manufacturer, a production date, and a model numberof the interchangeable lens 7, version information for softwareinstalled in the lens microcomputer 80, and firmware update information,and information regarding whether or not the interchangeable lens 7includes sections for correcting an image blur in, for example, the blurcorrection lens driving section 74 a and the blur detection section 84.If the interchangeable lens 7 includes sections for correcting an imageblur, the lens information further includes information regardingdetection performance of the blur detection section 84 such as a modelnumber, detection ability, and the like, information regardingcorrection performance (i.e., lens side correction performanceinformation) of the blur correction lens driving section 74 a such as amodel number, a maximum correctable angle, and the like, versioninformation for software for performing image blur correction, and thelike. Furthermore, the lens information includes information (i.e., lensside power consumption information) regarding power consumptionnecessary for driving the blur correction lens driving section 74 a, andinformation (i.e., lens side driving method information) regarding amethod for driving the blur correction lens driving section 74 a. Thenonvolatile memory 80 a can store information transmitted from the bodymicrocomputer 50. The information listed above may be stored in a memorysection of the lens microcomputer 80, instead of the nonvolatile memory80 a.

The focus lens group control section 81 includes an absolute positiondetection section 81 a for detecting an absolute position of the focuslens group 72 in the optical axis direction, and a relative positiondetection section 81 b for detecting a relative position of the focuslens group 72 in the optical axis direction. The absolute positiondetection section 81 a detects an absolute position of the focus lensgroup 72 in a case of the interchangeable lens 7. For example, theabsolute position detection section 81 a includes a several-bitcontact-type encoder substrate and a brush, and is capable of detectingan absolute position. The relative position detection section 81 bcannot detect the absolute position of the focus lens group 72 byitself, but can detect a moving direction of the focus lens group 72using, for example, a two-phase encoder. As for the two-phase encoder,two rotary pulse encoders, two MR devices, two Hall devices, or thelike, for alternately outputting binary signals with an equal pitchaccording to the position of the focus lens group 72 in the optical axisdirection are provided so that the phases of their respective pitchesare different from each other. The lens microcomputer 80 calculates therelative position of the focus lens group 72 in the optical axisdirection from an output of the relative position detection section 81b.

The blur detection section 84 includes an angular velocity sensor fordetecting movement of the interchangeable lens 7 due to hand shake andthe like. The angular velocity sensor outputs a positive/negativeangular velocity signal according to the direction in which theinterchangeable lens 7 moves, using, as a reference, an output in astate where the interchangeable lens 7 stands still. In this embodiment,two angular velocity sensors are provided to detect two directions,i.e., a yawing direction and a pitching direction. After being subjectedto filtering, amplification, and the like, the output angular velocitysignal is converted into a digital signal by the A/D conversion section,and then, is given to the lens microcomputer 80.

The blur correction lens unit control section 85 includes a movementamount detection section (not shown). The movement amount detectionsection is a detection section for detecting an actual movement amountof the blur correction lens 74. The blur correction lens unit controlsection 85 performs feedback control of the blur correction lens 74based on an output from the movement amount detection section.

An example in which the blur detection sections 56 and 84 and the blurcorrection units 45 and 74 a are provided to both of the camera body 4and the interchangeable lens 7 has been described. However, such blurdetection section and blur correction unit may be provided to either oneof the camera body 4 and the interchangeable lens 7. Alternatively, aconfiguration where such blur detection section and blur correction unitare not provided to any of the camera body 4 and the interchangeablelens 7 may be employed (in such a configuration, a sequence regardingthe above-described blur correction may be eliminated).

—Operation of Camera—

The camera 100 configured in the above-described manner has variousimage shooting modes and functions. Various image shooting modes andfunctions of the camera 100 and the operation thereof at the time ofeach of the modes and functions will be described hereinafter.

—AF Function—

When the release button 40 b is pressed halfway down, the camera 100performs AF to focus. To perform AF, the camera 100 has three autofocusfunctions, i.e., phase difference detection AF, contrast detection AF,and hybrid AF. A user can select one of the three autofocus functions byoperating the AF setting switch 40 c provided to the camera body 4.

Assuming that the camera system is in a normal shooting mode, theshooting operation of the camera system using each of the autofocusfunctions will be described hereinafter. The “normal shooting mode”herein means a most basic shooting mode of the camera 100 for shooting anormal picture.

(Phase Difference Detection AF)

First, the shooting operation of the camera system using phasedifference detection AF will be described with reference of FIGS. 10 and11.

When the power switch 40 a is turned on (Step Sa1), communicationbetween the camera body 4 and the interchangeable lens 7 is performed(Step Sa2). Specifically, power is supplied to the body microcomputer 50and each of other units in the camera body 4 to start up the bodymicrocomputer 50. At the same time, power is supplied to the lensmicrocomputer 80 and each of other units in the interchangeable lens 7via the electric contact pieces 41 a and 71 a to start up the lensmicrocomputer 80. The body microcomputer 50 and the lens microcomputer80 are programmed to transmit/receive information to/from each other atstart-up time. For example, lens information on the interchangeable lens7 is transmitted from the memory section of the lens microcomputer 80 tothe body microcomputer 50, and then is stored in the memory section ofthe body microcomputer 50.

Subsequently, the body microcomputer 50 performs positioning the focuslens group 72 at a predetermined reference position which has beendetermined in advance by the lens microcomputer 80 (Step Sa3), and inparallel to Step Sa3, changes the shutter unit 42 to an open state (StepSa4). Then, the process proceeds to Step Say, and the body microcomputer50 remains in a standby state until the release button 40 b is pressedhalfway down by the user.

Thus, light which has been transmitted through the interchangeable lens7 and has entered the camera body 4 passes through the shutter unit 42,is transmitted through the OLPF 43 also serving as an IR cutter, andthen enters the imaging unit 1. An object image formed at the imagingunit 1 is displayed on the image display section 44, so that the usercan see an erect image of an object via the image display section 44.Specifically, the body microcomputer 50 reads an electrical signal fromthe imaging device 10 via the imaging unit control section 52 atconstant intervals, and performs predetermined image processing on theread electrical signal. Then, the body microcomputer 50 generates animage signal, and controls the image display control section 55 to causethe image display section 44 to display a live view image.

Part of the light which has entered the imaging unit 1 is transmittedthrough the light transmitting portions 17, 17, . . . of the imagingdevice 10, and enters the phase difference detection unit 20.

In this case, when the release button 40 b is pressed halfway down(i.e., an S1 switch, which is not shown in the drawings, is turned on)by the user (Step Sa5), the body microcomputer 50 amplifies an outputfrom the line sensor 24 a of the phase difference detection unit 20, andthen performs operation by the arithmetic circuit, thereby determiningwhether or not an object image is in focus, whether the object is infront focus or back focus, and the Df amount (Step Sa6).

Thereafter, the body microcomputer 50 drives the focus lens group 72 viathe lens microcomputer 80 in the defocus direction by the Df amountobtained in Step Sa6 (Step Sa7).

In this case, the phase difference detection unit 2 of this embodimentincludes three sets of the condenser lens 21 a, the mask openings 22 a,22 a, the separator lens 23 a, and the line sensor 24 a, i.e., has threedistance measurement points at which phase difference detection isperformed. In phase difference detection in phase difference detectionAF or hybrid AF, the focus lens group 72 is driven based on an output ofthe line sensor 24 a of one of the sets corresponding to a distancemeasurement point arbitrarily selected by the user.

Alternatively, an automatic optimization algorithm may be installed inthe body microcomputer 50 beforehand in order to select one of thedistance measurement points located closest to the camera and drive thefocus lens group 72. Thus, the rate of the occurrence of focusing on thebackground of an object instead of the object can be reduced.

This selection of the distance measurement point is not limited to phasedifference detection AF. As long as the focus lens group 72 is drivenusing the phase difference detection unit 2, AF using any method can beemployed.

Then, it is determined whether or not an object image is in focus (StepSa8). Specifically, if the Df amount obtained based on the output of theline sensor 24 a is smaller than or equal to a predetermined value, itis determined that an object image is in focus (i.e., YES), and then,the process proceeds to Step Sa11. If the Df amount obtained based onthe output of the line sensor 24 a is larger than the predeterminedvalue, it is determined that an object image is not in focus (i.e., NO),the process returns to Step Sa6, and Steps Sa6-Sa8 are repeated.

As described above, detection of a focus state and driving of the focuslens group 72 are repeated and, when the Df amount becomes smaller thanor equal to the predetermined value, it is determined that an objectimage is in focus, and driving of the focus lens group 72 is halted.

In parallel to phase difference detection AF in Steps Sa6-Sa8,photometry is performed (Step Sa9), and image blur detection is alsostarted (Step Sa10).

Specifically, in Step Sa9, the amount of light entering the imagingdevice 10 is measured by the imaging device 10. That is, in thisembodiment, the above-described phase difference detection AF isperformed using light which has entered the imaging device 10 and hasbeen transmitted through the imaging device 10, and thus, photometry canbe performed using the imaging device 10 in parallel to theabove-described phase difference detection AF.

More specifically, the body microcomputer 50 loads an electrical signalfrom the imaging device 10 via the imaging unit control section 52, andmeasures the brightness of an object light, based on the electricalsignal, thereby performing photometry. According to a predeterminedalgorithm, the body microcomputer 50 determines, from a result ofphotometry, shutter speed and an aperture value which correspond to ashooting mode at a time of the exposure.

When photometry is terminated in Step Sa9, image blur detection isstarted in Step Sa10. Step Sa9 and Step Sa10 may be performed inparallel.

When the release button 40 b is pressed halfway down by the user,various information on shooting, as well as a shooting image, isdisplayed on the image display section 44, and thus, the user canconfirm each type of information via the image display section 44.

In Step Sa11, the body microcomputer 50 remains in a standby state untilthe release button 40 b is pressed all the way down (i.e., an S2 switch,which is not shown in the drawings, is turned on) by the user. When therelease button 40 b is pressed all the way down by the user, the bodymicrocomputer 50 once puts the shutter unit 42 into a closed state (StepSa12). Then, while the shutter unit 42 is kept in a closed state,electrical charge stored in the light receiving sections 11 b, 11 b, . .. of the imaging device 10 are transferred for the exposure, which willbe described later.

Thereafter, the body microcomputer 50 starts correction of an imageblur, based on communication information between the camera body 4 andthe interchangeable lens 7 or any information specified by the user(Step Sa13). Specifically, the blur correction lens driving section 74 ain the interchangeable lens 7 is driven based on information of the blurdetection section 56 in the camera body 4. According to the intention ofthe user, any one of (i) use of the blur detection section 84 and theblur correction lens driving section 74 a in the interchangeable lens 7,(ii) use of the blur detection section 56 and the blur correction unit45 in the camera body 4, and (iii) use of the blur detection section 84in the interchangeable lens 7 and the blur correction unit 45 in thecamera body 4 can be selected.

By starting driving of the image blur correction sections at a time whenthe release button 40 b is pressed halfway down, the movement of anobject desired to be in focus is reduced, and thus, phase differencedetection AF can be performed with higher accuracy.

The body microcomputer 50 stops down, in parallel to starting of imageblur correction, the aperture section 73 by the lens microcomputer 80 soas to attain an aperture value calculated based on a result ofphotometry in Step Sa9 (Step Sa14).

Thus, when the image blur correction is started and the apertureoperation is terminated, the body microcomputer 50 puts the shutter unit42 into an open state, based on the shutter speed obtained from theresult of photometry in Step Sa9 (Step Sa15). In the above-describedmanner, the shutter unit 42 is put into an open state, so that lightfrom the object enters the imaging device 10, and electrical charge isstored in the imaging device 10 only for a predetermined time (StepSa16).

The body microcomputer 50 puts the shutter unit 42 into a closed state,based on the shutter speed, to terminate the exposure (Step Sa17). Afterthe termination of the exposure, in the body microcomputer 50, imagedata is read out from the imaging unit 1 via the imaging unit controlsection 52 and then, after performing predetermined image processing onthe image data, the image data is output to the image display controlsection 55 via the image reading/recording section 53. Thus, a shootingimage is displayed on the image display section 44. The bodymicrocomputer 50 stores the image data in the image storage section 58via the image recording control section 54, as necessary.

Thereafter, the body microcomputer 50 terminates image blur correction(Step Sa18), and releases the aperture section 73 (Step Sa19). Then, thebody microcomputer 50 puts the shutter unit 42 into an open state (StepSa20).

When a reset operation is terminated, the lens microcomputer 80 notifiesthe body microcomputer 50 of the termination of the reset operation. Thebody microcomputer 50 waits for receiving reset termination informationfrom the lens microcomputer 80 and the termination of a series ofprocessings after the exposure. Thereafter, the body microcomputer 50confirms that the release button 40 b is not in a pressed state, andterminates a shooting sequence. Then, the process returns to Step Sa5,and the body microcomputer 50 remains in a standby state until therelease button 40 b is pressed halfway down.

When the power switch 40 a is turned off (Step Sa21), the bodymicrocomputer 50 shifts the focus lens group 72 to a predeterminedreference position (Step Sa22), and puts the shutter unit 42 into aclosed state (Step Sa23). Then, operation of the body microcomputer 50and other units in the camera body 4, and the lens microcomputer 80 andother units in the interchangeable lens 7 is halted.

As described above, in shooting operation of the camera system usingphase difference detection AF, photometry is performed by the imagingdevice 10 in parallel to autofocusing based on the phase differencedetection unit 20. Specifically, the phase difference detection unit 20receives light transmitted through the imaging device 10 to obtaindefocus information, and thus, whenever the phase difference detectionunit 20 obtains defocus information, the imaging device 10 is irradiatedwith light from an object. Therefore, photometry is performed usinglight transmitted through the imaging device 10 in autofocusing. Bydoing the above-described operation, a photometry sensor does not haveto be additionally provided, and photometry can be performed before therelease button 40 b is pressed all the way down, so that a time(hereinafter also referred to as a “release time lag”) from a time pointwhen the release button 40 b is pressed all the way down to a time pointwhen the exposure is terminated can be reduced.

Moreover, even in a configuration in which photometry is performedbefore the release button 40 b is pressed all the way down, byperforming photometry in parallel to autofocusing, increase inprocessing time after the release button 40 b is pressed halfway downcan be prevented. In such a case, a mirror for guiding light from anobject to a photometry sensor or a phase difference detection unit doesnot have to be provided.

Conventionally, part of light from an object to an imaging apparatus isguided to a phase difference detection unit provided outside the imagingapparatus by a mirror or the like. In contrast, according to thisembodiment, a focus state can be detected by the phase differencedetection unit 20 using light guided to the imaging unit 1 as it is, andthus, the focus state can be detected with very high accuracy.

(Contrast Detection AF)

Next, the shooting operation of the camera system using contrastdetection AF will be described with reference to FIG. 12.

When the power switch 40 a is turned on (Step Sb1), communicationbetween the camera body 4 and the interchangeable lens 7 is performed(Step Sb2), the focus lens group 72 is positioned at a predeterminedreference position (Step Sb3), the shutter unit 42 is put into an openstate (Step Sb4) in parallel to Step Sb3, and then, the bodymicrocomputer 50 remains in a standby state until the release button 40b is pressed halfway down (Step Sb5). The above-described steps, i.e.,Steps Sb1-Sb5, are the same as Steps Sa1-Sa5 in phase differencedetection AF.

When the release button 40 b is pressed halfway down by the user (StepSb5), the body microcomputer 50 drives the focus lens group 72 via thelens microcomputer 80 (Step Sb6). Specifically, the body microcomputer50 drives the focus lens group 72 so that a focal point of an objectimage is moved in a predetermined direction (e.g., toward an object)along the optical axis.

Then, the body microcomputer 50 obtains a contrast value for the objectimage, based on an output from the imaging device 10 received by thebody microcomputer 50 via the imaging unit control section 52 todetermine whether or not the contrast value is reduced (Step Sb7). Ifthe contrast value is reduced (i.e., YES), the process proceeds to StepSb8. If the contrast value is increased (i.e., NO), the process proceedsto Step Sb9.

Reduction in contrast value means that the focus lens group 72 is drivenin an opposite direction to the direction in which the object image isbrought in focus. Therefore, when the contrast value is reduced, thefocus lens group 72 is reversely driven so that the focal point of theobject image is moved in an opposite direction to the predetermineddirection (e.g., toward the opposite side to the object) along theoptical axis (Step Sb8). Thereafter, it is determined whether or not acontrast peak is detected (Step Sb10). During a period in which thecontrast peak is not detected (i.e., NO), reverse driving of the focuslens group 72 (Step Sb8) is repeated. When a contrast peak is detected(i.e., YES), reverse driving of the focus lens group 72 is halted, andthe focus lens group 72 is moved to a position where the contrast valuehas reached the peak. Then, the process proceeds to Step Sa11.

On the other hand, when the focus lens group 72 is driven in Step Sb6and the contrast value is increased, the focus lens group 72 is drivenin the direction in which the object image is brought in focus.Therefore, driving of the focus lens group 72 is continued (Step Sb9),and it is determined whether or not a peak of the contrast value isdetected (Step Sb10). Consequently, during a period in which thecontrast peak is not detected (i.e., NO), driving of the focus lensgroup 72 (Step Sb9) is repeated. When a contrast peak is detected (i.e.,YES), driving of the focus lens group 72 is halted, and the focus lensgroup 72 is moved to a position where the contrast value has reached thepeak. Then, the process proceeds to Step Sa11.

As has been described, in the contrast detection method, the focus lensgroup 72 is driven tentatively (Step Sb6). Then, if the contrast valueis reduced, the focus lens group 72 is reversely driven to search forthe peak of the contrast value (Steps Sb8 and Sb10). If the contrastvalue is increased, driving of the focus lens group 72 is continued tosearch for the peak of the contrast value (Steps Sb9 and Sb10).

In parallel to this contrast detection AF (i.e., Steps Sb6-Sb10),photometry is performed (Step Sb11) and image blur detection is started(Step Sb12). Steps Sb11 and Sb12 are the same as Steps Sa9 and Sa10 inphase difference detection AF.

In Step Sa11, the body microcomputer 50 remains in a standby state untilthe release button 40 b is pressed all the way down by the user. A flowof steps after the release button 40 b is pressed all the way down isthe same as that of phase difference detection AF.

In this contrast detection AF, a contrast peak can be directly obtained,and thus, unlike phase difference detection AF, various correctionoperations such as release back correction (for correcting anout-of-focus state related to the degree of aperture) and the like arenot necessary, so that highly accurate focusing performance can beachieved. However, to detect the peak of a contrast value, the focuslens group 72 has to be driven until the focus lens group 72 is moved soas to exceed the peak of the contrast value once. Accordingly, the focuslens group 72 has to be once moved to a position where the focus lensgroup 72 exceeds the peak of the contrast value and then be moved backto a position corresponding to the detected peak of the contrast value,and thus, a backlash generated in a focus lens group driving system dueto the operation of driving the focus lens group 72 in back and forthdirections has to be removed.

(Hybrid AF)

Subsequently, the shooting operation of the camera system using hybridAF will be described with reference to FIG. 13.

Steps (i.e., Steps Sc1-Sc5) from the step in which the power switch 40 ais turned on to the step in which the release button 40 b is pressedhalfway down are the same as Steps Sa1-Sa5 in phase difference detectionAF.

When the release button 40 b is pressed halfway down by the user (StepSc5), the body microcomputer 50 amplifies an output from the line sensor24 a of the phase difference detection unit 20, and then performsoperation by the arithmetic circuit, thereby determining whether or notan object image is in focus (Step Sc6). Furthermore, the bodymicrocomputer 50 determines where an object image is formed, i.e.,whether the object is in front focus or back focus, and the Df amount,and then, obtains defocus information (Step Sc7). Thereafter, theprocess proceeds to Step Sc10.

In parallel to Steps Sc6 and Sc7, photometry is performed (Step Sc8) andimage blur detection is started (Step Sc9). Steps Sc6 and Sc7 are thesame as Steps Sa9 and Sa10 in phase difference detection AF. Thereafter,the process proceeds to Step Sc10. Note that, after Step Sc9, theprocess may also proceed to Step Sa11, instead of Sc10.

As decried above, in this embodiment, using light which has entered theimaging device 10 and has been transmitted through the imaging device10, the above-described focus detection based on a phase difference isperformed. Thus, in parallel to the above-describe focus detection,photometry can be performed using the imaging device 10.

In Step Sc10, the body microcomputer 50 drives the focus lens group 72,based on the defocus information obtained in Step Sc7.

The body microcomputer 50 determines whether or not a contrast peak isdetected (Step Sc11). During a period in which the contrast peak is notdetected (i.e., NO), driving of the focus lens group 72 (Step Sc10) isrepeated. When a contrast peak is detected (i.e., YES), driving of thefocus lens group 72 is halted, and the focus lens group 72 is moved to aposition where the contrast value has reached the peak. Then, theprocess proceeds to Step Sa11.

Specifically, in Steps Sc10 and Sc11, it is preferable that, based onthe defocus direction and the defocus amount calculated in Step Sc7,after the focus lens group 72 is moved at high speed, the focus lensgroup 72 is moved at lower speed and a contrast peak is detected.

In this case, it is preferable that an moving amount of the focus lensgroup 72 which is moved based on the calculated defocus amount (i.e., aposition to which the focus lens group 72 is moved) is set to bedifferent from that in Step Sa1 in phase difference detection AF.Specifically, in Step Sa1 in phase difference detection AF, the focuslens group 72 is moved to a position which is estimated as a focusposition, based on the defocus amount. In contrast, in Step Sc10 inhybrid AF, the focus lens group 72 is driven to a position shiftedforward or backward from the position estimated as a focus position,based on the defocus amount. Thereafter, in hybrid AF, a contrast peakis detected while the focus lens group 72 is driven toward the positionestimated as the focus position.

In Step Sa11, the body microcomputer 50 remains in a standby state untilthe release button 40 b is pressed all the way down by the user. A flowof steps after the release button 40 b is pressed all the way down isthe same as that of phase difference detection AF.

As has been described, in hybrid AF, first, defocus information isobtained by the phase difference detection unit 20, and the focus lensgroup 72 is driven based on the defocus information. Then, a position ofthe focus lens group 72 at which a contrast value calculated based on anoutput from the imaging device 10 reaches a peak is detected, and thefocus lens group 72 is moved to the position. Thus, defocus informationcan be detected before driving the focus lens group 72, and therefore,unlike contrast detection AF, the step of tentatively driving the focuslens group 72 is not necessary. This allows reduction in processing timefor autofocusing. Moreover, an object image is brought in focus bycontrast detection AF eventually, and therefore, particularly, an objecthaving a repetitive pattern, an object having extremely low contrast,and the like can be brought in focus with higher accuracy than in phasedifference detection AF.

Since defocus information is obtained by the phase difference detectionunit 20 using light transmitted through the imaging device 10,photometry can be performed by the imaging device 10 in parallel to thestep of obtaining defocus information by the phase difference detectionunit 20 although hybrid AF includes phase difference detection. As aresult, a mirror for dividing part of light from an object to detect aphase difference does not have to be provided, and a photometry sensordoes not have to be additionally provided. Furthermore, photometry canbe performed before the release button 40 b is pressed all the way down.Therefore, a release time lag can be reduced. In the configuration inwhich photometry is performed before the release button 40 b is pressedall the way down, photometry can be performed in parallel to the step ofobtaining defocus information, thereby preventing increase in processingtime after the release button 40 b is pressed halfway down.

—Variations—

In the foregoing description, aperture operation is performed after therelease button 40 b is pressed all the way down and immediately beforeexposure. On the other hand, the following description is directed to avariation in which aperture operation is performed before the releasebutton 40 b is pressed all the way down and before autofocus in phasedifference detection AF and hybrid AF.

(Phase Difference Detection AF)

Specifically, first, shooting operation of the camera system using phasedifference detection AF according to the variation will be describedwith reference of FIG. 14.

Steps (i.e., Steps Sd1-Sd5) from the step in which the power switch 40 ais turned on to the step in which the body microcomputer 50 remains in astandby state until the release button 40 b is pressed halfway down arethe same as Steps Sa1-Sa5 in phase difference detection AF describedabove.

When the release button 40 b is pressed halfway down by the user (StepSd5), image blur detection is started (Step Sd6). In parallel to StepSd6, photometry is performed (Step Sd7). Steps Sd5 and Sd6 are the sameas Steps Sa9 and Sa11) in phase difference detection AF.

Thereafter, based on a result of the photometry performed in Step Sd7,an aperture value during exposure is obtained, and it is determinedwhether or not the obtained aperture value is larger than apredetermined aperture threshold (Step Sd8). If the obtained aperturevalue is larger than the predetermined aperture threshold (i.e., YES),the process proceeds to Step Sd10. If the obtained aperture value issmaller than or equal to the predetermined aperture threshold (i.e.,NO), the process proceeds to Step Sd9. In Step Sd9, the bodymicrocomputer 50 drives the aperture section 73 via the lensmicrocomputer 80 so as to attain the obtained aperture value.

Here, the predetermined aperture threshold is set at an aperture valueat which defocus information can be obtained based on an output of theline sensor 24 a of the phase difference detection unit 20.Specifically, in a case where the aperture value obtained based on theresult of photometry is larger than the aperture threshold, if theaperture section 73 is stopped down to the aperture value, obtainingdefocus information by the phase difference detection unit 20, whichwill be describe later, cannot be performed. Therefore, in this case,the aperture section 73 is not stopped down and the process proceeds toStep Sd10. On the other hand, if the aperture value obtained based onthe result of photometry is smaller than or equal to the aperturethreshold, the aperture section 73 is stopped down to the aperture valueand the process proceeds to Step Sd10.

In Steps Sd10-Sd12, as in Steps Sa6-Sa8 in phase difference detection AFdescribed above, the body microcomputer 50 obtains defocus informationbased on an output from the line sensor 24 a of the phase differencedetection unit 20 (Step Sd10). Based on the defocus information, thefocus lens group 72 is driven (Step Sd11), and then it is determinedwhether or not an object image is in focus (Step Sd12). After the objectimage has been in focus, the process proceeds to Step Sa11.

In Step Sa11, the body microcomputer 50 remains in a standby state untilthe release button 40 b is pressed all the way down by the user. A flowof steps after the release button 40 b has been pressed all the way downis the same as in phase difference detection AF described above.

It should be noted that aperture operation of the aperture section 73 isperformed in Step Sa14 only when the aperture value obtained based onthe result of photometry in Step Sd8 is larger than the predeterminedaperture threshold. Specifically, aperture operation of the aperturesection 73 has been performed in Step Sd9 if it is determined that theaperture value obtained based on the result of photometry in Step Sd8 issmaller than or equal to the predetermined aperture threshold. Thus, itis unnecessary to perform Step Sa14.

In this manner, in shooting operation of the camera system using phasedifference detection AF according to this variation, if the aperturevalue during exposure obtained based on the result of photometry is atsuch a value that allows phase difference detection AF to be performed,the aperture section 73 is stopped down before autofocus prior to theexposure. Thus, aperture operation of the aperture section 73 does nothave to be performed after the release button 40 b has been pressed allthe way down, thereby reducing a release time lag.

(Hybrid AF)

Next, shooting operation of the camera system using hybrid AF accordingto the variation will be described with reference of FIG. 15.

Steps (i.e., Steps Se1-Se5) from the step in which the power switch 40 ais turned on to the step in which the body microcomputer 50 remains in astandby state until the release button 40 b is pressed halfway down arethe same as Steps Sa1-Sa5 in phase difference detection AF describedabove.

When the release button 40 b is pressed halfway down by the user (StepSe5), image blur detection is started (Step Se6). In parallel to StepSe6, photometry is performed (Step Se7). Steps Se6 and Se7 are the sameas Steps Sa9 and Sa10 in phase difference detection AF.

Thereafter, based on a result of the photometry performed in Step Se7,an aperture value during exposure is obtained, and it is determinedwhether or not the obtained aperture value is larger than apredetermined aperture threshold (Step Se8). If the obtained aperturevalue is larger than the predetermined aperture threshold (i.e., YES),the process proceeds to Step Se10. If the obtained aperture value issmaller than or equal to the predetermined aperture threshold (i.e.,NO), the process proceeds to Step Se9. In Step Se9, the bodymicrocomputer 50 drives the aperture section 73 via the lensmicrocomputer 80 so as to attain the obtained aperture value.

Here, the predetermined aperture threshold is set at an aperture valueat which a peak of a contrast value calculated from an output from theimaging device 10 can be detected. Specifically, in a case where theaperture value obtained based on the result of photometry is larger thanan aperture threshold, if the aperture section 73 is stopped down to theaperture value, detection of the contrast peak, which will be describelater, cannot be performed. Therefore, in this case, the aperturesection 73 is not stopped down and the process proceeds to Step Se10. Onthe other hand, if the aperture value obtained based on the result ofphotometry is smaller than or equal to the aperture threshold, theaperture section 73 is stopped down to the aperture value and theprocess proceeds to Step Se10.

In Steps Se10-Se12, as in Steps Sc6, Sc7, Sc10, and Sc11 in normalhybrid AF described above, the body microcomputer 50 obtains defocusinformation based on an output from the line sensor 24 a of the phasedifference detection unit 20 (Steps Se10 and Sell). Based on the defocusinformation, the focus lens group 72 is driven (Step Se12). Then, acontrast peak is detected, and the focus lens group 72 is moved to aposition where the contrast value has reached the peak (Step Se13).

Subsequently, in Step Sa11, the body microcomputer 50 remains in astandby state until the release button 40 b is pressed all the way downby the user. A flow of steps after the release button 40 b has beenpressed all the way down is the same as in normal phase differencedetection AF described above.

It should be noted that aperture operation of the aperture section 73 isperformed in Step Sa14 only when the aperture value obtained based onthe result of photometry in Step Se8 is larger than the predeterminedaperture threshold. Specifically, aperture operation of the aperturesection 73 has been performed in Step Se9 if it is determined that theaperture value obtained based on the result of photometry in Step Se8 issmaller than or equal to the predetermined aperture threshold. Thus, itis unnecessary to perform Step Sa14.

In this manner, in shooting operation of the camera system using hybridAF according to this variation, if the aperture value during exposureobtained based on the result of photometry is at such a value thatallows contrast detection AF to be performed, the aperture section 73 isstopped down before autofocus prior to the exposure. Thus, apertureoperation of the aperture section 73 does not have to be performed afterthe release button 40 b has been pressed all the way down, therebyreducing a release time lag.

—Continuous Shooting Mode—

In the foregoing description, one image is captured every time therelease button 40 b is pressed all the way down. The camera 100 also hasa continuous shooting mode in which a plurality of images are capturedby pressing the release button 40 b all the way down at a time.

The continuous shooting mode will be described hereinafter withreference to FIGS. 16 and 17. The following description is directed tohybrid AF according to the variation. It should be noted that thecontinuous shooting mode is not limited to hybrid AF of the variation,and may be applied to any operation such as phase difference detectionAF, contrast detection AF, hybrid AF, and phase difference detection AFof the variation.

Steps (i.e., Steps Sf1-Sf13) from the step in which the power switch 40a is turned on to the step in which the release button 40 b is pressedhalfway down so that the focus lens group 72 is moved to a positionwhere the contrast value reaches a peak are the same as Steps Se1-Se13in hybrid AF of the variation.

After the focus lens group 72 has been moved to the position where thecontrast value reaches a peak, the body microcomputer 50 causes thedistance between two object images formed on the line sensor 24 a atthis time (i.e., when the object images are brought in focus by contrastdetection AF) to be stored in the memory section (Step Sf14).

Thereafter, in Step Sf15, the body microcomputer 50 remains in a standbystate until the release button 40 b is pressed all the way down by theuser. When the release button 40 b is pressed all the way down by theuser, exposure is performed in the same manner as in Steps Sa12-Sa17 inphase difference detection AF.

Specifically, the body microcomputer 50 once puts the shutter unit 42into a closed state (Step Sf16), and correction of an image blur isstarted (Step Sf17). If the aperture section 73 is not stopped down inStep Sf9, the aperture section 73 is stopped down based on a result ofphotometry (Step Sf18), and then the shutter unit 42 is put into an openstate (Step Sf19) to start exposure (Step Sf20). Thereafter, in thiscase, the shutter unit 42 is put into a closed state (Step Sf21) toterminate the exposure.

After the exposure, it is determined whether or not pressing the releasebutton 40 b all the way down is canceled (Step Sf22). If the pressingthe release button 40 b all the way down is canceled (i.e., YES), theprocess proceeds to Steps Sf29 and Sf30. If the pressing the releasebutton 40 b all the way down is continued (i.e., NO), the processproceeds to Step Sf23 to perform continuous shooting.

While the release button 40 b is put all the way down, the bodymicrocomputer 50 puts the shutter unit 42 into an open state (StepSf23), and phase difference detection AF is performed (Steps Sf24-Sf26).

Specifically, a focus state of an object image in the imaging device 10is detected via the phase difference detection unit 20 (Step Sf24),defocus information is obtained (Step Sf25). Based on the defocusinformation, the focus lens group 72 is driven (Step Sf26).

Here, in hybrid AF before the release button 40 b is pressed all the waydown, defocus information is obtained by comparing the distance betweentwo object images formed on the line sensor 24 a with a predeterminedreference distance (Step Sf11). In contrast, in Steps Sf24 and Sf25after the release button 40 b has been pressed all the way down, a focusstate and defocus information are obtained by comparing the distancebetween two object images formed on the line sensor 24 a with thedistance of two object images formed on the line sensor 24 a stored inStep Sf14 after contrast detection AF in hybrid AF.

After phase difference detection AF has been performed in theabove-described manner, the body microcomputer 50 determines whether ornot it is time to output a signal (i.e., an exposure start signal) forstarting exposure from the body microcomputer 50 to the shutter controlsection 51 and the imaging unit control section 52 (Step Sf27). Thistiming of outputting of an exposure start signal is a timing ofcontinuous shooting in the continuous shooting mode. If it is not timeto output an exposure start signal (i.e., NO), phase differencedetection AF is repeated (Steps Sf24-Sf26). If it is time to output anexposure start signal (i.e., YES), driving of the focus lens group 72 isstopped (Step Sf28), and exposure is performed (Step Sf20).

After the focus lens group 72 has been stopped and before exposure isstarted, it is necessary to remove electrical charge accumulated in thelight receiving sections 11 b, 11 b, . . . of the imaging device 10during phase difference detection AF. Accordingly, electrical charge inthe light receiving sections 11 b, 11 b, . . . is removed by anelectronic shutter, or the shutter unit 42 is once put into a closedstate so as to remove electrical charge in the light receiving sections11 b, 11 b, . . . and then is put into an open state, and then exposureis started.

After the exposure, it is determined whether or not pressing the releasebutton 40 b all the way down is canceled (Step Sf22). While the releasebutton 40 b is pressed all the way down, phase difference detection AFand exposure are repeated (Steps Sf23-Sf28, Sf20, and Sf21).

On the other hand, if the pressing the release button 40 b all the waydown is canceled, correction of an image blur is terminated (Step Sf29),and in addition, the aperture section 73 is opened (Step Sf30), therebyputting the shutter unit 42 into an open state (Step Sf31).

After completion of the resetting, when a shooting sequence isterminated, the process returns to Step Say, and the body microcomputer50 remains in a standby state until the release button 40 b is pressedhalfway down.

When the power switch 40 a is turned off (Step Sf32), the bodymicrocomputer 50 shifts the focus lens group 72 to a predeterminedreference position (Step Sf33), and puts the shutter unit 42 into aclosed state (Step Sf34). Then, operation of the body microcomputer 50and other units in the camera body 4, and the lens microcomputer 80 andother units in the interchangeable lens 7 is halted.

In this manner, in shooting operation of the camera system in thecontinuous shooting mode, phase difference detection AF can be performedamong periods of exposure in continuous shooting, thereby achievinghighly accurate focusing performance.

In addition, since autofocus at this time is phase difference detectionAF, defocus direction can be instantaneously obtained. Accordingly, evenin a short period between continuous shootings, the camera system canfocus instantaneously.

Further, even in phase difference detection AF, no movable mirrors forphase difference detection do not have to be provided, unlikeconventional techniques. Accordingly, a release time lag can be reduced,and power consumption can be reduced. Moreover, in a conventionaltechnique, a release time lag is caused by moving a movable mirror upand down. Thus, if an object is a moving object, it is necessary tocapture an image with predictions made on movement of the moving objectin the release time lag. In contrast, in this embodiment, since norelease time lag exists for up and down movement of a movable mirror,the camera system can focus, while following movement of an object untilimmediately before exposure.

Further, in phase difference detection AF during continuous shooting,the distance between two object images on the line sensor 24 a which arein focus by contrast detection AF when the release button 40 b ispressed halfway down, is used as a reference distance between two objectimages on the line sensor 24 a for determining whether or not an objectimage is in focus. Thus, highly accurate autofocus suitable for actualapparatus and actual shooting conditions can be performed.

The method employed in shooting a first frame in the continuous shootingmode is not limited to hybrid AF, and may be phase difference detectionAF or contrast detection AF. Note that in the case of phase differencedetection AF, Step Sf14 is not performed, and in Steps Sf24 and Sf25, afocus state and defocus information are obtained by comparing thedistance between two object images formed on the line sensor 24 a withthe predetermined reference distance.

This description is not limited to the continuous shooting mode. Innormal shooting, if an object is a moving object, even after the imagehas been in focus, phase difference detection AF may be performed untilthe release button 40 b is pressed all the way down.

—Low Contrast Mode—

The camera 100 of this embodiment is configured to switch the type ofautofocus according to the contrast of object images. Specifically, thecamera 100 includes a low contrast mode in which shooting is performedunder low contrast.

The low contrast mode will be described hereinafter with reference toFIG. 18. The following description is directed to operation using hybridAF. The low contrast mode is not limited to hybrid AF, and may beapplied to any operation such as phase difference detection AF, contrastdetection AF, phase difference detection AF of the variation, and hybridAF of the variation.

Steps (i.e., Steps Sg1-Sg5) from the step in which the power switch 40 ais turned on to the step in which the body microcomputer 50 remains in astandby state until the release button 40 b is pressed halfway down arethe same as Steps Sa1-Sa5 in phase difference detection AF.

When the release button 40 b is pressed halfway down by the user (StepSg5), the body microcomputer 50 amplifies an output from the line sensor24 a of the phase difference detection unit 20, and then performsoperation with the arithmetic circuit (Step Sg6). Then, it is determinedwhether object images are in a low contrast state or not (Step Sg7).Specifically, it is determined whether or not the contrast value islarge enough to detect the positions of two object images formed on theline sensor 24 a based on an output from the line sensor 24 a.

Consequently, if the contrast value is large enough to detect thepositions of the two object images (i.e., NO), it is determined that theobjects are not in a low contrast state. Then, the process proceeds toStep Sg8, and hybrid AF is performed. Steps Sg8-Sg10 are the same asSteps Sc7, Sc10, and Sc11 in hybrid AF.

On the other hand, if the contrast value is not large enough to detectthe positions of two object images (i.e., YES), it is determined thatthe objects are in a low contrast state. Then, the process proceeds toStep Sg11, and contrast detection AF is performed. Steps Sg11-Sg15 arethe same as Steps Sb6-Sb10 in contrast detection AF.

After hybrid AF or contrast detection AF has been performed in theabove-described manner, the process proceeds to Step Sa11.

In parallel to the autofocus operation (i.e., Steps Sg6-Sg15),photometry is performed (Step Sg16), and image blur detection is started(Step Sg17). Steps Sg16 and Sg17 are the same as Steps Sa9 and Sa10 inphase difference detection AF. Thereafter, the process proceeds to StepSa11.

In Step Sa11, the body microcomputer 50 remains in a standby state untilthe release button 40 b is pressed all the way down by the user. A flowof steps after the release button 40 b has been pressed all the way downis the same as in normal hybrid AF.

Specifically, in the low contrast mode, if the contrast in shooting ishigh enough to perform phase difference detection AF, hybrid AF isperformed. On the other hand, if the contrast in shooting is not highenough to perform phase difference detection AF, contrast detection AFis performed.

In this embodiment, first, it is determined whether or not a focus statecan be detected by a phase difference detection method based on anoutput of the line sensor 24 a of the phase difference detection unit 20so that one of hybrid AF and contrast detection AF is selected. However,the present invention is not limited to this process. For example, thefollowing configuration may be employed. Specifically, after the releasebutton 40 b has been pressed halfway down and before a phase differencefocal point is detected (i.e., between Steps Sg5 and Sg6 in FIG. 18), acontrast value may be obtained based on an output of the imaging device10 so as to determine whether or not the contrast value obtained fromthe output of the imaging device 10 is larger than a predeterminedvalue. Here, the predetermined value is set at a contrast value largeenough to detect the positions of object images formed on the linesensor 24 a. Specifically, if the contrast value obtained from theoutput of the imaging device 10 is larger than or equal to a value atwhich a focus state can be detected by the phase difference detectionmethod, hybrid AF may be performed. If the contrast value obtained fromthe output of the imaging device 10 is smaller than the value at which afocus state can be detected by the phase difference detection method,contrast detection AF may be performed.

In this embodiment, if a focus state can be detected by the phasedifference detection method, hybrid AF is performed. Alternatively, inthis case, phase difference detection AF may be performed, instead.

In this manner, in the camera 100 including the imaging unit 1 in whichlight transmitted through the imaging device 10 is received by the phasedifference detection unit 20, phase difference detection AF (includinghybrid AF) and contrast detection AF can be performed without aconventional movable mirror for guiding light to the phase differencedetection unit. As a result, highly accurate focusing performance can beachieved by selecting phase difference detection AF or contrastdetection AF according to the contrast.

—AF Switching according to Type of Interchangeable Lenses—

The camera 100 of this embodiment is configured to switch the type ofautofocus according to the type of the interchangeable lenses 7 attachedto the camera body 4.

AF switching function according to the type of the interchangeablelenses will be described hereinafter with reference to FIG. 19. Thefollowing description is directed to hybrid AF. However, the AFswitching function according to the type of the interchangeable lensesis not limited to hybrid AF, and may be applied to any operation such asphase difference detection AF, contrast detection AF, phase differencedetection AF of the variation, and hybrid AF of the variation.

Steps (i.e., Steps Sh1-Sh5) from the step in which the power switch 40 ais turned on to the step in which the body microcomputer 50 remains in astandby state until the release button 40 b is pressed halfway down arethe same as Steps Sa1-Sa5 in phase difference detection AF.

When the release button 40 b is pressed halfway down by the user (StepSh5), photometry is performed (Step Sh6), and in parallel to Step Sh6,image blur detection is started (Step Sh7). Steps Sh6 and Sh7 are thesame as Steps Sa9 and Sa10 in phase difference detection AF. Thephotometry and the image blur detection may be performed in parallel toautofocus, which will be described later.

Thereafter, based on information from the lens microcomputer 80, thebody microcomputer 50 determines whether or not the interchangeablelenses 7 are third-party reflex telephoto lenses or smooth transitionfocus (STF) lenses (Step Sh8). If the interchangeable lenses 7 arethird-party reflex telephoto lenses or STF lenses (i.e., YES), theprocess proceeds to Step Sh13, and contrast detection AF is performed.Steps Sh13-Sh17 are the same as Steps Sb6-Sb10 in contrast detection AF.

If the interchangeable lenses 7 are neither third-party reflex telephotolenses nor STF lenses (i.e., NO), the process proceeds to Step Sh9, andhybrid AF is performed. Steps Sh9-Sh12 are the same as Steps Sc6, Sc7,Sc10, and Sc11 in hybrid AF.

After contrast detection AF or hybrid AF has been performed in theabove-described manner, the process proceeds to step Sa11.

In Step Sa11, the body microcomputer 50 remains in a standby state untilthe release button 40 b is pressed all the way down by the user. A flowof steps after the release button 40 b is pressed all the way down isthe same as that of hybrid AF.

Specifically, if the interchangeable lenses 7 are third-party reflextelephoto lenses or STF lenses, phase difference detection might not beperformed with accuracy. Thus, hybrid AF (specifically, phase differencedetection AF) is not performed, and contrast detection AF is performed.On the other hand, if the interchangeable lenses 7 are neitherthird-party reflex telephoto lenses nor STF lenses, hybrid AF isperformed. More specifically, the body microcomputer 50 determineswhether coincidence of the optical axes of the interchangeable lenses 7sufficient for performing phase difference detection AF is ensured ornot. Hybrid AF is performed only for the interchangeable lenses 7 inwhich coincidence of the optical axes thereof sufficient for performingphase difference detection AF is ensured. On the other hand, contrastdetection AF is performed for the interchangeable lenses 7 in whichcoincidence of the optical axes thereof sufficient for performing phasedifference detection AF is not ensured.

As described above, in the camera 100 including the imaging unit 1 inwhich light transmitted through the imaging device 10 is received by thephase difference detection unit 20, phase difference detection AF(including hybrid AF) and contrast detection AF can be performed withouta conventional movable mirror for guiding light to the phase differencedetection unit. As a result, highly accurate focusing performance can beachieved by selecting phase difference detection AF or contrastdetection AF according to the type of the interchangeable lenses 7.

In this embodiment, one of hybrid AF and contrast detection AF isselected by determining whether or not the interchangeable lenses 7 arethird-party reflex telephoto lenses or STF lenses. However, the presentinvention is not limited to this configuration. One of hybrid AF andcontrast detection AF may be selected by determining whether theinterchangeable lenses 7 are third-party lenses or not, irrespective ofwhether or not the interchangeable lenses 7 are reflex telephoto lensesor STF lenses.

In this embodiment, hybrid AF is performed if the interchangeable lenses7 are neither third-party reflex telephoto lenses nor STF lenses.Alternatively, in this case, phase difference detection AF may beperformed, instead.

Third Embodiment

Now, a camera as an imaging apparatus as an imaging apparatus accordingto a third embodiment of the present invention will be described.

As illustrated in FIG. 20, a camera 200 according to the thirdembodiment includes a finder optical system 6.

—Configuration of Camera Body—

In addition to the configuration of the camera body 4 of the secondembodiment, a camera body 204 includes: the finder optical system 6 forvisually identifying an object image through a finder 65; and asemi-transparent quick return mirror 46 for guiding light entering frominterchangeable lenses 7 to the finder optical system 6.

The camera body 204 has a finder shooting mode in which shooting isperformed with an object image visually identified through the finderoptical system 6 and a live view shooting mode in which shooting isperformed with an object image visually identified through an imagedisplay section 44. The camera body 204 includes a finder-mode settingswitch 40 g. The camera body 204 is set in the finder shooting mode byturning the finder-mode setting switch 40 g on, and is set in the liveview shooting mode by turning the finder-mode setting switch 40 g off.

The finder optical system 6 includes: a finder screen 61 on which lightreflected on the quick return mirror 46 is formed into an image; apentaprism 62 for converting an object image projected on the finderscreen 61 into an erect image; an eyepiece 63 for visually identifyingthe projected object image in an enlarged manner; an in-finder displaysection 64 for displaying various information in the field of view ofthe finder; and the finder 65 provided at the back side of the camerabody 204.

That is, an object image formed on the finder screen 61 can be observedfrom the finder 65 through the pentaprism 62 and the eyepiece 63.

In addition to the configuration of the body control section 5 of thesecond embodiment, a body control section 205 includes a mirror controlsection 260 for controlling flip-up operation of the quick return mirror46, which will be described later, based on a control signal from thebody microcomputer 50.

The quick return mirror 46 is a semi-transparent mirror capable ofreflecting or transmitting incident light, is located in front of theshutter unit 42, and is configured to be rotatable between thereflection position (indicated by the solid lines in FIG. 20) on anoptical path X extending from an object to the imaging unit 1 and aretreat position (indicated by the chain double-dashed lines in FIG. 20)which is located out of the optical path X and close to the finderoptical system 6. At the reflection position, the quick return mirror 46divides incident light into reflected light reflected toward the finderoptical system 6 and transmitted light transmitted toward the back sideof the quick return mirror 46.

Specifically, the quick return mirror 46 is disposed in front of theshutter unit 42 (i.e., closer to an object), and is supported to berotatable about the axis Y extending horizontally in front of an upperportion of the shutter unit 42. The quick return mirror 46 is flippedtoward the retreat position by a bias spring (not shown). In addition,the quick return mirror 46 is moved to the reflection position bywinding the bias spring with a motor (not shown) for opening/closing theshutter unit 42. The quick return mirror 46 which has been moved to thereflection position is locked in the reflection position with, forexample, an electromagnet. When this locked state is canceled, the quickreturn mirror 46 is moved, while rotating, to the retreat position bythe force of the bias spring.

That is, to guide part of incident light to the finder screen 61, thebias spring is wound with the motor, and thereby, the quick returnmirror 46 is moved to the reflection position. On the other hand, toguide all the incident light to the imaging unit 1, a locked state with,for example, an electromagnet is canceled, and thereby, the quick returnmirror 46 is moved, while rotating, to the retreat position by theelastic force of the bias spring.

As illustrated in FIG. 21, the quick return mirror 46 is coupled to alight shield plate 47. The light shield plate 47 operates insynchronization with the quick return mirror 46. When the quick returnmirror 46 is in the retreat position, the light shield plate 47 coversthe quick return mirror 46 from below the quick return mirror 46 (i.e.,from the side of the quick return mirror 46 toward the optical path Xextending from an object to the imaging unit 1). Thus, it is possible toprevent light entering from the finder optical system 6 from reachingthe imaging unit 1 when the quick return mirror 46 is in the retreatposition.

Specifically, the light shield plate 47 includes a first light shieldplate 48 rotatably coupled to an end of the quick return mirror 46opposite to the rotation axis Y and a second light shield plate 49rotatably coupled to the first light shield plate 48. The first lightshield plate 48 has a first cam follower 48 a. On the other hand, thecamera body 204 has a first cam groove 48 b with which the first camfollower 48 a is engaged. The second light shield plate 49 has a secondcam follower 49 a. On the other hand, the camera body 204 has a secondcam groove 49 b with which the second cam follower 49 a is engaged.

That is, when the quick return mirror 46 is rotated, the first lightshield plate 48 follows the quick return mirror 46 to move, and thesecond light shield plate 49 follows the first light shield plate 48 tomove. At this time, the first and second light shield plates 48 and 49move in synchronization with the quick return mirror 46 with the firstand second cam followers 48 a and 49 a respectively guided by the firstand second cam grooves 48 b and 49 b.

Consequently, when the quick return mirror 46 is in the retreatposition, the first and second light shield plates 48 and 49 aredisposed to form a single flat plate below the quick return mirror 46,as illustrated in FIG. 21(A), and block light between the quick returnmirror 46 and the shutter unit 42, i.e., the imaging unit 1. At thistime, as the quick return mirror 46 is, the first and second lightshield plates 48 and 49 are located out of the optical path X.Accordingly, the first and second light shield plates 48 and 49 do notaffect light entering the imaging unit 1 from an object.

As the quick return mirror 46 moves from the retreat position to thereflection position, the first and second light shield plates 48 and 49gradually bend from the flat plate state, as illustrated in FIG. 21(B).Then, when the quick return mirror 46 is rotated to the reflectionposition, the first and second light shield plates 48 and 49 bend toface each other, as illustrated in FIG. 21(C). At this time, the firstand second light shield plates 48 and 49 are located out of the opticalpath X, and at the side opposite the finder screen 61 with the opticalpath X sandwiched therebetween. Accordingly, when the quick returnmirror 46 is in the reflection position, the first and second lightshield plates 48 and 49 do not affect light reflected from the quickreturn mirror 46 to the finder optical system 6 and light transmittedthrough the quick return mirror 46.

As described above, the quick return mirror 46 is made semi-transparent,and the light shield plate 47 is provided. Thus, in the finder shootingmode, it is possible to visually identify an object image with thefinder optical system 6, while allowing light to reach the imaging unit1, before shooting. During the shooting, it is possible to prevent lightentering from the finder optical system 6 from reaching the imaging unit1 with the light shield plate 47, while guiding light from the object tothe imaging unit 1. In the live view shooting mode, the light shieldplate 47 can prevent light entering from the finder optical system 6from reaching the imaging unit 1.

—Operation of Camera—

The camera 200 configured as described above has two shooting modes,i.e., a finder shooting mode and a live view shooting mode, which differfrom each other in visually identifying an object. Operation of thecamera 200 in each of the two shooting modes will be describedhereinafter.

—Finder Shooting Mode—

First, shooting operation of the camera system in the finder shootingmode will be described hereinafter with reference to FIGS. 22 and 23.

Steps in which the power switch 40 a is turned on (Step Si1), therelease button 40 b is pressed halfway down by the user (Step Si5), therelease button 40 b is pressed all the way down by the user (Step Si11),and then the shutter unit 42 is once put into a closed state (Step Si12)are basically the same as Steps Sa1-Sa12 in phase difference detectionAF of the second embodiment.

Note that when the power switch 40 a is turned on, the quick returnmirror 46 is in the reflection position on the optical path X.Accordingly, light which has entered the camera body 204 is partiallyreflected to enter the finder screen 61.

Light which has entered the finder screen 61 is formed as an objectimage. This object image is converted into an erect image by thepentaprism 62, and enters the eyepiece 63. That is, unlike the secondembodiment in which an object image is displayed on the image displaysection 44, the user can observe an erect image of an object through theeyepiece 63. At this time, the image display section 44 displays not anobject image but various information on shooting.

When the release button 40 b is pressed halfway down by the user (StepSi5), various information (e.g., information on AF and photometry, whichwill be described later) on shooting are displayed on the in-finderdisplay section 64 observed through the eyepiece 63. That is, the usercan see various information on shooting with the in-finder displaysection 64 as well as the image display section 44.

Since the quick return mirror 46 is semi-transparent, part of lightwhich has entered the camera body 204 is guided to the finder opticalsystem 6 by the quick return mirror 46, but the other part of the lightis transmitted through the quick return mirror 46 to enter the shutterunit 42. Then, when the shutter unit 42 is put into an open state (StepSi4), light transmitted through the quick return mirror 46 enters theimaging unit 1. Consequently, it is possible to perform autofocus (StepsSi6-Si8) and photometry (Step Si9) with the imaging unit 1, whileenabling visual identification of an object image through the finderoptical system 6.

Specifically, in Steps Si6-Si8, phase difference detection AF isperformed based on an output from the phase difference detection unit 20of the imaging unit 1, and in parallel to the phase difference detectionAF, photometry can be performed based on an output from the imagingdevice 10 of the imaging unit 1 in Step Si9.

In detection of a phase difference focal point in Step Sib, since objectimage light is transmitted through the quick return mirror 46, theoptical length is increased by the value corresponding to the thicknessthereof. Accordingly, the phase detection width of the phase differencefocal point detection section differs between a case where the quickreturn mirror 46 retreats from the position on the object image opticalpath to a shooting state and a case where the quick return mirror 46 isin the reflection position. Thus, in the finder shooting mode in whichthe quick return mirror 46 is placed on the object image optical path,defocus information is output with a phase detection width changed by apredetermined value from the phase detection width in phase differencefocal point detection of the first embodiment (i.e., the phase detectionwidth in phase difference focal point detection in hybrid AF in the liveview shooting mode, which will be described later). The phase detectionwidth is a phase difference as a reference for calculating that adefocus amount is 0 (zero), i.e., determining that an object image is infocus.

Steps Si6-Si8 in which phase difference detection AF is performed arethe same as Steps Sa6-Sa8 in phase difference detection AF of the secondembodiment.

In Step Si9, the imaging device 10 measures the amount of light enteringthe imaging device 10. In this embodiment, not all of light from anobject enters the imaging device 10, unlike the second embodiment. Thus,the body microcomputer 50 corrects an output from the imaging device 10based on reflection properties of the quick return mirror 46, andobtains the amount of light from the object.

After the release button 40 b is pressed all the way down by the user(Step Si11) and the shutter unit 42 is once put into a closed state(Step Si12), flip-up of the quick return mirror 46 to the retreatposition is performed in Step Si15, in parallel to a start of image blurcorrection (Step Si13) and aperture operation of the aperture section 73(Step Si14).

Thereafter, in Steps Si16-Si18, exposure is performed in the same manneras in Steps Sa15-Sa17 in phase difference detection AF of the secondembodiment.

After the exposure, in parallel to termination of image blur correction(Step Si19) and opening of the aperture section 73 (Step Si20), thequick return mirror 46 is moved to the reflection position in Step Si21.Thus, the user can visually identify an object image again through thefinder optical system 6.

Subsequently, the shutter unit 42 is put into an open state (Step Si22).In this manner, when a shooting sequence is terminated after completionof resetting, the process returns to Step Si5, and the bodymicrocomputer 50 is in a standby state until the release button 40 b ispressed halfway down.

Steps Si23-Si25 after the power switch 40 a is turned off are the sameas Steps Sa21-Sa23 in phase difference detection AF of the secondembodiment.

As described above, even in the configuration allowing visualidentification of an object image through the finder optical system 6 byguiding light from the object to the finder optical system 6 using thequick return mirror 46, since the phase difference detection unit 20 fordetecting a phase difference using light transmitted through the imagingdevice 10 is provided in the imaging unit 1, it is possible to performvisual identification of an object image through the finder opticalsystem 6, while performing phase difference detection AF and photometryin parallel, by forming the quick return mirror 46 to besemi-transparent to allow part of light which has entered the quickreturn mirror 46 to reach the imaging unit 1. In this manner, it isunnecessary to additionally provide a reflection mirror for phasedifference detection AF and a photometry sensor, and in addition,photometry can be performed in parallel to autofocus, thereby reducing arelease time lag.

—Live View Shooting Mode—

Now, shooting operation of the camera system in the live view shootingmode will be described hereinafter with reference to FIGS. 24 and 25.

Steps (i.e., Steps Sj1-Sj4) from the step in which the power switch 40 ais turned on to the step in which the shutter unit 42 is put into anopen state are the same as operation in hybrid AF of the secondembodiment.

Here, in the camera 200, immediately after the power switch 40 a isturned on, the quick return mirror 46 is in the reflection position.Thus, in Step Sj5, the body microcomputer 50 flips the quick returnmirror 46 up to the retreat position.

Consequently, light entering the camera body 4 from an object is notguided to the finder optical system 6, but is transmitted through theshutter unit 42 and then through the OLPF 43 also serving as an IRcutter, and enters the imaging unit 1. An object image formed on theimaging unit 1 is displayed on the image display section 44 so that theuser can see the object image through the image display section 44. Partof light which has entered the imaging unit 1 is transmitted through theimaging device 10 to enter the phase difference detection unit 20.

When the release button 40 b is pressed halfway down by the user (StepSj6), hybrid AF is performed, unlike in the finder shooting mode. StepsSj7, Sj8, Sj11, and Sj12 in hybrid AF are the same as Steps Sc6, Sc7,Sc10, and Sc11 in hybrid AF of the second embodiment.

The foregoing description is not limited to hybrid AF, and contrastdetection AF or phase difference detection AF may be performed.

In parallel to hybrid AF described above, photometry is performed (StepSj9), and image blur detection is started (Step Sj10). Steps Sj9 andSj10 are the same as Steps Sc8 and Sc9 in hybrid AF of the secondembodiment.

As described above, when the release button 40 b is pressed halfway downby the user, various information (e.g., information on AF andphotometry) on shooting is displayed on the image display section 44.

Thereafter, steps from the step in which the release button 40 b ispressed all the way down by the user (Step Sj13) to the step in whichexposure is terminated to complete resetting (Step Sj22) are basicallythe same as Steps Si11-Si22 in the finder shooting mode, except that thestep of moving the quick return mirror 46 to the retreat position afterputting the shutter unit 42 into a closed state (corresponding to StepSi15) is not performed, and that the step of moving the quick returnmirror 46 to the reflection position after putting the shutter unit 42into a closed state to terminate exposure (corresponding to Step Si21)is not performed.

In this embodiment, when the power switch 40 a is turned off (StepSj23), the focus lens group 72 is moved to the reference position (StepSj24), and in parallel to the step of putting the shutter unit 42 into aclosed state (Step Sj25), the quick return mirror 46 is moved to thereflection position in Step Sj26. Then, operation of the bodymicrocomputer 50 and other units in the camera body 204, and the lensmicrocomputer 80 and other units in the interchangeable lens 7 ishalted.

Shooting operation of the camera system in the live view shooting modeis the same as shooting operation of the camera 100 of the secondembodiment except for operation of the quick return mirror 46.Specifically, although the foregoing description is directed to hybridAF, various types of shooting operation of the second embodiment may beperformed. In such cases, the same advantages can be achieved.

Other Embodiments

The above embodiments may have the following configurations.

Specifically, in the third embodiment, the finder optical system 6 isprovided. However, the present invention is not limited to thisconfiguration. For example, instead of the finder optical system 6, anelectronic view finder (EVF) may be provided. Specifically, a smallimage display section made of, for example, liquid crystal is disposedat such a position in the camera body 204 that allows an object image tobe visually identified through the finder, so as to display image dataobtained by the imaging unit 1 on the image display section. Then, evenin the absence of the complicated finder optical system 6, shooting canbe performed with an image viewed through the finder. This configurationdoes not need the quick return mirror 46. Shooting operation in thiscase is the same as in the camera 100 of the second embodiment exceptthat two image display sections are provided.

The second and third embodiments are directed to the configurations ineach of which the imaging unit 1 is installed in the camera. However,the present invention is not limited to these configurations. Forexample, the imaging unit 1 may be installed in a video camera.

An example of shooting operation of a video camera will now bedescribed. When the power switch 40 a is turned on, the aperture sectionand the shutter unit are opened, and an image capturing is started inthe imaging device 10 of the imaging unit 1. Then, photometry and WBadjustment are performed to be optimal for a live view display, and alive view image is displayed on the image display section. In thismanner, in parallel to imaging by the imaging device 10, a focus stateis detected based on an output of the phase difference detection unit 20incorporated in the imaging unit 1, and the focus lens group iscontinuously driven in accordance with, for example, motion of anobject. In this manner, the camera is in a standby state until a RECbutton is pressed with display of a live view image and phase differencedetection AF continuously performed in the above-described manner. Whenthe REC button is pressed, image data obtained by the imaging device 10is recorded with phase difference detection AF repeated. Then, a focusstate can always be maintained, and in addition, it is unnecessary toperform driving (wobbling) of the focus lens in the optical axisdirection to a small degree, unlike a conventional digital video camera,and thus, it is also unnecessary to drive actuator, such as a motor,having a heavy electrical load.

In the above description, when the release button 40 b is pressedhalfway down by the user (i.e., the S1 switch is turned on), AF isstarted. Alternatively, AF may be started before the release button 40 bis pressed halfway down. In addition, AF does not have to be terminatedwhen it is determined that an object is in focus, and may be continuedafter it is determined that an object is in focus, or may be continuedwithout determination that an object is in focus. A specific examplewill be described hereinafter. In FIGS. 10 and 11, after the shutterunit 42 is opened in Step Sa4, phase difference focal point detection inStep Sa6 and driving of the focus lens in Step Sa1 are repeated. Inparallel to these steps, determination in Step Sa5, photometry in StepSa9, starting of image blur detection in Step Sa10, and determination inStep Sa11 are performed. Thus, a focus state can be obtained before therelease button 40 b is pressed halfway down by the user. For example, ifthe foregoing operation is performed with display of a live view image,the live view image can be displayed in a focus state. In addition, theuse of phase difference detection AF allows display of a live view imageand phase difference detection AF to be performed together. Suchoperation may be applied to the camera as an “always AF mode.” The statein the “always AF mode” may be switched between on and off.

In the foregoing embodiments, the imaging unit 1 is installed in thecamera. However, the present invention is not limited to thisconfiguration. The camera including the imaging unit 1 is an example ofcameras in which exposure of an imaging device and phase differencedetection by a phase difference detection unit can be simultaneouslyperformed. A camera according to the present invention is not limitedthereto, but may have a configuration in which object light is guided toboth of an imaging device and a phase difference detection unit by, forexample, an optical separation device (e.g., a prism or asemi-transparent mirror) for separating light to the image device.Moreover, a camera in which part of each microlens of an imaging deviceis used as a separator lens and separator lenses are arranged so thatpupil-divided object light can be received at light receiving sectionsmay be employed.

Note that the above-described embodiments are essentially preferableexamples which are illustrative and do not limit the present invention,its applications, and the scope of use of the invention.

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful for an imagingapparatus including an imaging device for performing photoelectricconversion.

1. An imaging apparatus, comprising: an imaging device configured toperform photoelectric conversion on received light and allow light topass therethrough; and a phase difference detection section configuredto perform phase difference detection on received light which has passedthrough the imaging device, wherein the imaging device includes acolor-purpose light receiving section configured to obtain colorinformation and an brightness-purpose light receiving section configuredto obtain brightness information and receive a larger amount of lightthan the color-purpose light receiving section, and the phase differencedetection section performs phase difference detection on received lightwhich has passed through at least the brightness-purpose light receivingsection.
 2. The imaging apparatus of claim 1, wherein the imaging devicefurther includes a substrate on which the color-purpose light receivingsection and the brightness-purpose light receiving section are provided,and the substrate allows light to pass therethrough.
 3. The imagingapparatus of claim 2, wherein the substrate has a thin portion having athickness smaller than that of a portion of the substrate around thethin portion, and light passes through the substrate via the thinportion.
 4. The imaging apparatus of claim 3, wherein the substrate hasmultiple ones of the thin portion, the phase difference detectionsection includes separator lenses each configured to divide light whichhas passed through the thin portion into beams and sensors eachconfigured to detect a phase difference between the beams divided by theseparator lenses, and the number of the separator lenses and the numberof the sensors are equal to the number of the multiple ones of the thinportion.
 5. The imaging apparatus of one of claims 1 to 4, wherein theimaging device includes a plurality of repeat units each made of thesingle brightness-purpose light receiving section and three of thecolor-purpose light receiving section, the three color-purpose lightreceiving sections allows light beams of three different colors torespectively pass therethrough, and the repeat units are regularlyarranged.
 6. The imaging apparatus of claim 5, further comprising acontrol section configured to generate an image signal based on anoutput of the imaging device, wherein the control section interpolatesinformation on a color of a pixel of the brightness-purpose lightreceiving section using an output of the color-purpose light receivingsection located around the brightness-purpose light receiving section.7. The imaging apparatus of claim 5, wherein a color filter is providedin the color-purpose light receiving section, and no color filter isprovided in the brightness-purpose light receiving section.
 8. Theimaging apparatus of claim 7, wherein the three color-purpose lightreceiving sections in each of the repeat units are respectively a greenlight receiving section in which a green color filter is provided, a redlight receiving section in which a red color filter is provided, and ablue light receiving section in which a blue color filter is provided,in each of the repeat units, the single brightness-purpose lightreceiving section and the three color-purpose light receiving sectionsare arranged in two rows and two columns, and in each of the repeatunits, the brightness-purpose light receiving section and the greenlight receiving section are located in one diagonal direction, whereasthe red light receiving section and the blue light receiving section arelocated in another diagonal direction.